GIFT   OF 


THE  SCIENTIFIC  WORK 

OF 

MORRIS  LOEB 


THE  SCIENTIFIC  WORK 

OF 

MORRIS  LOEB 


THE  SCIENTIFIC  WORK 

OF 

MORRIS  LOEB 

FORMERLY   PROFESSOR  OF   CHEMISTRY   AND 

DIRECTOR   OF   THE   HAVEMEYER   CHEMICAL  LABORATORY 

AT  NEW   YORK  UNIVERSITY 

EDITED   BY 

THEODORE  W.  RICHARDS 

PROFESSOR   OF   CHEMISTRY   AND   DIRECTOR   OF 

THE  WOLCOTT  GIBBS  MEMORIAL  LABORATORY 

AT   HARVARD   UNIVERSITY 


CAMBRIDGE 

HARVARD  UNIVERSITY  PRESS 
1913 


COPYRIGHT,    1913,   BY    HARVARD   UNIVERSITY   PRESS 
ALL   RIGHTS  RESERVED 


PREFACE 

THIS  volume  is  published  as  a  memorial  to  Morris  Loeb, 
a  man  of  rare  gifts  who  was  called  in  his  prime  from  his 
many-sided  activities.  The  book  will  serve  to  make  more 
accessible  the  thoughtful  and  suggestive  writings  of  one  of 
the  American  pioneers  of  the  new  physical  chemistry. 

All  the  publications  of  the  late  Professor  Loeb  bearing 
upon  scientific  topics  have  here  been  brought  together, 
except  a  few  brief  reviews  in  Italian  possessing  only  tran- 
sient interest;  and  there  have  been  added  such  parts  of 
several  essays  found  in  manuscript  as  he  might  have  been 
willing  to  have  printed.  The  collected  papers  have  been 
divided  into  two  groups;  the  first  includes  those  of  a  gen- 
eral character  (such  as  essays,  lectures,  and  reviews),  and 
the  second  those  recording  the  results  of  his  original  experi- 
mental researches,  which  are  more  technical  in  their  nature 
and  less  generally  comprehensible.  This  division  into  two 
groups  was  made  in  order  that  essays  having  general  interest 
should  not  be  lost  to  the  average  reader  by  being  hidden 
among  scientific  papers  beyond  his  comprehension. 

In  each  group  the  papers  have  been  arranged  in  chrono- 
logical order.  Of  those  found  in  manuscript,  parts  of  three 
discussions  of  the  same  subject  have  been  welded  together  so 
as  to  make  one  consistent  essay  and  placed  at  the  beginning 
of  the  first  group  under  the  title  "The  Fundamental  Ideas 
of  Physical  Chemistry."  The  first  part  of  this  essay  was 
evidently  given  as  the  introductory  lecture  of  a  course  on 
physical  chemistry  at  Clark  University  in  1889.  Each  of 
the  three  papers  was  fragmentary;  but  fortunately  the  gaps 


271811 


vi  PREFACE 

occurred  in  different  places,  so  that  it  was  possible  to  con- 
struct almost  entirely  in  the  author's  own  words  a  fairly 
consistent  whole.  Although  these  fragments  were  not  deemed 
worthy  of  publication  by  their  author,  and  although  doubt- 
less he  would  have  preferred  to  revise  them  before  printing, 
it  has  seemed  worth  while  to  publish  them  because  they 
formed  one  of  the  very  first  presentations  of  the  new  phys- 
ical chemistry  on  this  side  of  the  Atlantic. 

The  popular  address  on  "Atoms  and  Molecules  "  also  was 
found  in  manuscript,  and  like  the  preceding  essay,  has  had 
incorporated  into  it  several  scattered  paragraphs  upon  the 
same  subject  from  other  incomplete  notes.  Thus  it  is  hoped 
that  all  of  his  written  work  on  this  subject  that  is  worthy 
of  printing  has  been  preserved  in  readable  form. 

Another  paper  printed  for  the  first  time  is  that  on  Sir 
Isaac  Newton,  which  is  of  interest  in  showing  the  author's 
appreciation  of  the  value  of  abstract  scientific  research. 

The  only  other  important  paper  found  in  manuscript 
(placed  under  the  title  "  Chemistry  and  Civilization,"  at  the 
end  of  the  first  group  of  papers)  was  intended  by  Professor 
Loeb  to  be  the  introduction  to  a  proposed  comprehensive  book 
upon  the  usefulness  of  the  science  in  its  widest  sense.  Upon 
this  book  he  was  working  at  the  time  of  his  death ;  and  one 
cannot  but  poignantly  regret,  after  reading  the  introductory 
chapter,  that  the  completion  of  the  project  was  denied  him. 

Two  of  the  researches  included  in  the  second  group  were 
published  both  in  German  and  in  English;  in  these  cases  both 
versions  are  reprinted,  because  the  translations  are  evidently 
the  author's  work,  and  differ  in  several  details  from  the 
originals. 

In  each  of  the  scientific  articles  included  in  the  second 
part  of  the  book,  the  page  numbers  of  the  original  publica- 
tion are  inserted  in  brackets  at  the  proper  places,  to  show 


PREFACE  vii 

where  each  page  begins  and  ends.  This  is  done  for  the  con- 
venience of  commentators  wishing  to  refer  to  the  original 
articles.  All  the  papers  have  been  reprinted  essentially  in  the 
form  used  by  the  author.  The  historical  advantage  of  this 
practice  is  obvious;  and  although  usage  in  nomenclature, 
notation,  and  spelling  has  somewhat  changed  during  twenty- 
five  years,  the  older  forms  cannot  in  any  of  the  present 
instances  give  rise  to  misunderstanding. 

After  the  scientific  contributions,  Professor  Loeb's  labora- 
tory manual  of  experiments  for  the  elementary  course  in 
inorganic  chemistry  at  New  York  University  is  printed  as  an 
appendix,  together  with  the  description  of  a  brief  series  of  ex- 
periments upon  the  speed  of  reactions.  These  are  included 
not  only  for  the  sake  of  completeness,  but  also  because  they 
may  be  suggestive  to  others  confronted  with  the  interesting 
but  difficult  task  of  giving  elementary  instruction. 

A  complete  chronological  list  of  all  the  separate  essays  is 
given  at  the  end  of  the  volume,  with  the  references  to  the 
original  sources;  and  an  index  of  names  completes  the  book. 

Other  manuscripts  and  notebooks  found  in  his  laboratories 
contained  much  that  was  almost  ready  for  publication,  but 
probably  nothing  more  that  he  himself  would  have  con- 
sidered as  ready  to  appear  in  print.  The  preliminary  search 
among  these  papers  was  conducted  at  the  request  of  his 
family  by  Professor  Charles  Baskerville,  of  the  College  of  the 
City  of  New  York,  and  Mr.  D.  D.  Berolzheimer,  a  former 
student  of  Professor  Loeb's  and  the  librarian  of  The  Chemists' 
Club;  thanks  are  due  to  both  for  their  valuable  assistance  in 
making  a  preliminary  selection  and  arrangement  of  the  ma- 
terial, and  to  the  latter,  as  well  as  to  Professor  G.  S.  Forbes, 
for  their  help  in  reading  the  proofs.  To  Professors  Charles 
Loring  Jackson,  Elmer  P.  Kohler  and  Gregory  P.  Baxter 
also  the  editor  is  grateful  for  advice.  T.  W.  R. 


CONTENTS 

INTRODUCTION:  THE  LIFE  AND  CHARACTER  OF  MORRIS  LOEB  .       .    xv 

PART  I 
LECTURES,  ADDRESSES,  AND  REVIEWS 

THE  FUNDAMENTAL  IDEAS  OF  PHYSICAL  CHEMISTRY     ....      3 

OSMOTIC    PRESSURE    AND    THE    DETERMINATION    OF    MOLECULAR 
WEIGHTS 21 

ELECTROLYTIC  DISSOCIATION:  A  REVIEW  OF  THE  HYPOTHESIS  OF 
SVANTE  ARRHENIUS 30 

REVIEW  OF  OSTWALD'S  GRUNDRISS  DER  ALLGEMEINEN  CHEMIE     .  45 

THE  PROVINCE  OF  A  GREAT  ENDOWMENT  FOR  RESEARCH  ...  46 

ATOMS  AND  MOLECULES 50 

HYPOTHESIS  OF  RADIANT  MATTER 64 

REPORT  OF   THE   COMMITTEE  OF    THE   OVERSEERS   TO   VISIT   THE 

CHEMICAL  LABORATORY  OF  HARVARD  COLLEGE     ....    78 

THE  CONDITIONS  AFFECTING  CHEMISTRY  IN  NEW  YORK     ...    93 

SIR  ISAAC  NEWTON 101 

OLIVER  WOLCOTT  GIBBS 108 

THE  CHEMISTS'  CLUB,  NEW  YORK 118 

THE  CHEMISTS'  BUILDING 121 

ADDRESS  AS  PRESIDENT  OF  THE  CHEMISTS'  BUILDING  COMPANY    .  128 
THE  COAL-TAR  COLORS  .      .  132 


x  CONTENTS 

THE  PERIODIC  LAW 143 

THE  EIGHTH  INTERNATIONAL  CONGRESS  OF  APPLIED  CHEMISTRY  .  152 
CHEMISTRY  AND  CIVILIZATION 156 

PART  II 
ORIGINAL  EXPERIMENTAL  INVESTIGATIONS 

UEBER   DIE   EINWIRKUNG  VON   PHOSGEN  AUF  AETHENDIPHENYL- 
DIAMIN 169 

UEBER  AMIDINDERIVATE 171 

DAS  PHOSGEN  UNO  SEINE  ABKOMMLINGE  NEBST  EINIGEN  BEITRAGEN 

zu  DEREN  KENNTNISS 177 

DAS  PHOSGEN:  LITTERATUR-VERZEICHNISS 205 

DAS  PHOSGEN:  EXPERIMENTELLER  THEIL 209 

THE  MOLECULAR  WEIGHT  OF  IODINE  IN  ITS  SOLUTIONS   .      .      .230 
UEBER  DEN  MOLEKULARZUSTAND  DBS  GELOSTEN  JODS       .      .      .  239 

THE  USE  OF  ANILINE  AS  AN  ABSORBENT  OF  CYANOGEN  IN  GAS 
ANALYSIS 248 

ZUR  KlNETIK  DER  IN  LoSUNG  BEFINDLICHEN  KORPER       .       .       .251 

THE  RATES  OF  TRANSFERENCE  AND  THE  CONDUCTING  POWER  OF 

CERTAIN  SILVER  SALTS 273 

THE  USE  OF  THE  GOOCH  CRUCIBLE  AS  A  SILVER  VOLTAMETER      .  293 
Is  CHEMICAL  ACTION  AFFECTED  BY  MAGNETISM? 295 

APPARATUS  FOR  THE  DELINEATION  OF  CURVED  SURFACES,  IN  ILLUS- 
TRATION OF  THE  PROPERTIES  OF  GASES,  ETC 306 

NOTE  ON  THE  CRYSTALLIZATION  OF   SODIUM  IODIDE  FROM  ALCO- 
HOLS      308 

THE  VAPOR  FRICTION  OF  ISOMERIC  ETHERS 310 

ANALYSIS  OF  SOME  BOLIVIAN  BRONZES 312 

STUDIES  IN  THE  SPEED  OF  REDUCTIONS  ....  314 


CONTENTS  xi 

APPENDIX 

LABORATORY  MANUAL  PREPARED  FOR  STUDENTS  IN  ELEMENTARY 
INORGANIC  CHEMISTRY  AT  NEW  YORK  UNIVERSITY  ....  321 

EXPERIMENTS  ON  SPEED  OF  REACTION 338 

CHRONOLOGICAL  BIBLIOGRAPHY 340 

INDEX  OF  NAMES  .  .  345 


LIST  OF  ILLUSTRATIONS 

MORRIS  LOEB Frontispiece 

WOLCOTT  GIBBS   MEMORIAL  LABORATORY,  HARVARD 

UNIVERSITY opposite  page  92 

THE  CHEMISTS'  BUILDING,  52  EAST  FORTY-FIRST  STREET, 

NEW  YORK opposite  page  118 


THE  LIFE  AND  CHARACTER  OF  MORRIS 

LOEB 

IN  the  untimely  death  of  Morris  Loeb  our  country  lost  a 
man  of  rare  quality.  To  serve  mankind  was  the  ideal  of  his 
life,  and  loyalty  was  his  guide  in  the  fulfillment  of  this  service; 
few  men  in  so  short  a  span  of  years  have  been  able  to  ex- 
press so  largely  their  desire  by  deeds.  His  helpful  acts  and 
liberal  benefactions  were  modestly  carried  out;  they  were 
perhaps  hardly  appreciated  in  their  fullness  during  his  life- 
time by  any  except  those  who  came  nearest  to  him.  As  an 
ameliorator  of  the  lot  of  the  poor  of  New  York  he  was  in  the 
front  rank;  at  the  same  time  he  was  a  farseeing  enthusiast 
in  the  cause  of  science,  and  one  of  the  most  faithful  and 
generous  graduates  of  Harvard  University.  His  devotion 
to  his  Alma  Mater  makes  it  especially  appropriate  that  this 
volume  of  his  writings  should  appear  under  her  auspices. 

Among  his  various  interests  chemistry  was  foremost,  al- 
though the  responsibilities  of  a  great  fortune  and  its  attendant 
demands  prevented  him  from  devoting  as  much  time  to  re- 
search as  he  would  have  been  glad  to  give.  The  study  of  his 
work  as  disclosed  in  the  following  pages  will  show  a  mental 
attitude  unusually  thoughtful  and  philosophic,  alive  to  new 
ideas  and  yet  wisely  conservative.  His  conservatism  was  not 
of  a  reactionary  type,  because  he  was  ever  altruistic  in  his 
point  of  view.  His  constant  aim  was  to  support  that  which 
seemed  to  him  likely  to  contribute,  either  through  the  ad- 
vance of  science  or  in  any  other  way,  to  the  good  of  mankind. 

Morris  Loeb  was  born  fifty  years  ago  at  Cincinnati,  Ohio, 
on  May  23, 1863,  the  son  of  Solomon  and  Betty  (Gallenberg) 
Loeb.  His  father  was  one  of  the  founders  of  the  great  bank- 


xvi          THE  LIFE  AND  CHARACTER 

ing  firm  of  Kuhn,  Loeb  and  Company.  While  the  boy  was 
still  young,  his  parents  removed  to  New  York,  and  his 
primary  education  took  place  at  the  school  of  Dr.  Julius  Sachs 
in  that  city.  In  the  autumn  of  1879  he  entered  Harvard  Uni- 
versity and  graduated  there  with  the  degree  of  Bachelor  of 
Arts  in  1883. 

He  was  an  able  and  conscientious  student  in  college.  His 
interest  centred  at  first  in  the  older  discipline  of  the  classics, 
but  it  changed  to  the  newer  discipline  of  chemistry  and  phys- 
ics as  his  college  life  advanced.  His  experience  under  Charles 
Loring  Jackson  in  "Chemistry  1 "  during  his  Freshman  year 
seems  to  have  awakened  that  love  of  science  which,  fostered 
as  it  was  by  Wolcott  Gibbs  in  his  later  years,  determined  his 
life  work.  As  an  undergraduate  he  received  a  "Detur"  or 
prize  for  high  scholarship,  and  at  graduation  he  attained 
his  degree  "Magna  cum  Laude"  on  his  general  average,  as 
well  as  with  "Honorable  Mention"  in  chemistry  and  English 
composition.  His  best  chemical  work  in  college  was  done  in 
the  field  of  organic  chemistry  under  Henry  Barker  Hill, 
and  this  interest  was  continued  in  his  studies  immediately 
afterwards  in  Germany,  as  is  evidenced  in  his  first  two  scien- 
tific papers. 

During  the  period  of  his  stay  in  Berlin,  where  he  studied 
under  August  Wilhelm  von  Hofmann  and  received  the  de- 
gree of  Ph.D.  in  1887,  the  new  interest  in  physical  chemistry 
had  risen  above  the  intellectual  horizon  of  Germany,  and 
Loeb's  farsighted  intelligence  at  once  grasped  the  significance 
of  the  coming  science.  The  winter  after  he  received  his  de- 
gree, he  entered  the  University  of  Heidelberg  for  the  study 
of  physical  chemistry,  and  during  the  following  summer  he 
attended  the  University  of  Leipzig,  working  under  the  bril- 
liant new  leader,  Wilhelm  Ostwald,  and  in  collaboration  with 
his  able  assistant,  Walther  Nernst. 


OF  MORRIS  LOEB  xvii 

In  the  autumn  of  1888  Loeb  returned  to  America;  he  was 
now  so  thoroughly  imbued  with  a  passionate  love  for  science 
that  the  urgent  appeal  of  the  brilliant  position  in  banking 
which  was  open  to  him  was  not  heeded.  Instead  of  turning 
towards  finance  he  entered  upon  a  voluntary  private  assistant- 
ship  under  Wolcott  Gibbs,  who  had  recently  retired  from  his 
Rumford  Professorship  in  Harvard  University  and  as  Pro- 
fessor Emeritus  had  established  a  private  chemical  laboratory 
near  his  house  at  Newport,  Rhode  Island.  Their  mutual 
affection,  which  had  begun  years  before  when  both  were  at 
Harvard,  was  intensified  by  this  close  association;  and  it  is 
typical  of  the  characteristic  faithfulness  of  Loeb's  nature 
that  nearly  a  quarter  of  a  century  afterward  he  should  have 
suggested  the  naming  of  a  new  laboratory  for  research, 
founded  at  Harvard  by  him  and  his  brother  James  Loeb 
(of  the  class  of  1888),  in  honor  of  Gibbs. 

In  1889  the  young  physical  chemist  was  appointed  to  a 
docentship  in  Clark  University.  His  opening  lecture  there 
was  probably  the  essay  given  first  among  the  papers  included 
in  this  volume;  he  never  published  it  himself,  but  the  man- 
uscript remains  in  his  own  handwriting.  This  lecture  shows 
his  intelligent  appreciation  of  the  main  problems  of  the  new 
physical  chemistry  and  their  great  importance.  He  was  in- 
deed one  of  the  pioneers  in  America  in  this  new  field  of 
science,  and  his  influence  was  far-reaching. 

In  1891  he  was  elected  to  a  professorship  of  chemistry  in 
New  York  University,  and  four  years  afterwards  became  direc- 
tor of  the  chemical  laboratory  there,  an  office  which  he  held 
for  eleven  years.  His  resignation  in  1906  was  due  not  to  any 
weakening  of  his  interest  in  chemistry,  but  rather  to  the  pres- 
sure of  countless  other  demands  upon  his  time,  which  made 
the  routine  of  such  a  position  almost  if  not  quite  impossible. 

Much  of  his  energy  was  given  to  a  number  of  charitable 


xviii        THE  LIFE  AND  CHARACTER 

organizations;  for  his  keen  sympathy  with  human  suffering 
caused  him  to  be  ever  responsive  to  the  needs  of  the  un- 
fortunate. His  charitable  work,  like  his  generous  activity  in 
other  directions,  was  by  no  means  restricted  to  his  own  race, 
although  he  was  of  course  especially  devoted  to  associations 
which  had  as  their  object  the  improvement  of  the  lot  of  the 
great  mass  of  Hebrew  poor  in  New  York.  He  was  president 
of  the  United  Jewish  Charities  Building,  a  member  of  the 
American  Jewish  Committee,  a  trustee  of  the  Jewish  Theologi- 
cal Seminary  of  America,  and  was  at  one  time  president  of 
the  Jewish  Agricultural  and  Industrial  Aid  Society.  He  was, 
moreover,  president  and  one  of  the  founders  of  the  Solomon 
and  Betty  Loeb  Home  for  Convalescents,  erected  in  mem- 
ory of  his  parents. 

Another  enterprise  demanding  much  of  his  time  was  The 
Chemists'  Club  of  New  York,  the  welfare  of  which  he  did 
much  to  promote.  Here  again  he  was  characteristically  earn- 
est in  his  effort  to  help  in  every  possible  way  those  for  whom 
he  felt  himself  especially  responsible.  Twice  he  was  vice- 
president  and  twice  president  of  the  club,  and  it  was  during 
his  first  presidency  in  1909  that  the  idea  of  housing  the 
club  and  its  admirable  library  in  a  dignified  building  first 
took  shape.  He  not  only  gave  outright  many  things  to  the 
unique  building  which  rose  under  his  direction,  but  also  was 
one  of  the  chief  stockholders  in  the  enterprise.  His  generous 
bequest  of  all  his  holdings  of  stock  in  the  building  to  the 
Chemists'  Building  Company  for  cancelation  cannot  but  do 
much  to  fortify  the  future  of  the  Club  and  help  towards  its 
permanent  existence. 

In  1908  he  was  appointed  one  of  the  committee  of  the  Har- 
vard Overseers  to  visit  the  Chemical  Laboratory.  As  usual  he 
entered  very  faithfully  into  this  new  responsibility  and,  unless 
in  foreign  lands,  attended  every  meeting  of  the  committee, 


OF  MORRIS  LOEB  xix 

although  such  attendance  involved  on  each  occasion  a  trip 
to  Boston.  Besides  making  this  sacrifice  of  time  and  energy 
in  behalf  of  his  beloved  University,  he  bore  always  in  mind 
the  difficulties  of  the  struggling  Division  of  Chemistry,  and 
frequent  letters,  often  written  in  his  own  hand  from  remote 
countries,  brought  valuable  suggestions  to  the  department 
and  attested  his  constant  interest  in  its  welfare  and  in  the 
growth  of  his  chosen  branch  of  science  at  Harvard.  As  al- 
ready stated,  it  was  upon  his  initiative,  through  the  generous 
gift  of  $50,000  from  his  brother  James  Loeb  and  himself, 
that  the  Wolcott  Gibbs  Memorial  Laboratory  for  research 
in  physical  and  inorganic  chemistry  was  founded  at  Harvard. 

Largely  through  his  interest  and  endeavor  the  Association 
of  Harvard  Chemists  was  formed,  from  among  the  alumni  of 
the  University;  and  his  hospitality  to  this  association  during 
the  Eighth  International  Congress  of  Applied  Chemistry  in 
1912  will  long  be  remembered  by  those  who  were  fortunate 
enough  to  be  his  guests  at  that  time. 

His  devotion  to  the  Congress  was  characteristically  strong. 
Since  delegates  from  all  over  the  world  had  been  invited  to 
this  continent,  he  felt  that  Americans  should  take  especial 
pains  to  make  the  meeting  a  success.  Although  he  had  only 
just  returned  from  a  long  trip  to  South  America,  undertaken 
with  the  hope  of  stimulating  interest  in  the  undertaking,  he 
threw  himself  with  self-sacrificing  enthusiasm  into  the  work 
of  preparing  for  the  reception  of  the  foreign  guests  in  Wash- 
ington and  New  York. 

Besides  being  a  member  of  the  Congress  (and  an  unusually 
helpful  one),  Professor  Loeb  was  a  fellow  of  the  New  York 
Academy  of  Sciences  and  of  the  American  Association  for 
the  Advancement  of  Science,  and  a  member  of  the  Amer- 
ican Chemical  Society,  the  German  Chemical  Society,  the 
American  Electrochemical  Society,  and  the  New  York  Elec- 


xx  THE  LIFE  AND  CHARACTER 

trical  Association.  He  received  the  honorary  degree  of  Doc- 
tor of  Science  from  Union  College  in  1911. 

During  the  twenty-nine  years  between  his  graduation  and 
his  death,  Morris  Loeb  published  thirty  papers,  reviews, 
and  essays.  Many  of  these  depended  upon  experimental  work 
carried  out  at  the  universities  in  Berlin,  Heidelberg,  Leipzig, 
Worcester,  and  New  York,  or  in  the  private  laboratories 
which  he  himself  established,  after  his  retirement  from  active 
teaching,  in  New  York  and  on  his  beautiful  country  estate 
at  Sea  Bright,  New  Jersey.  For  the  reasons  already  set 
forth,  the  extent  and  scope  of  his  experimental  researches 
were  far  less  than  he  wished;  but,  even  so,  the  work  forms  a 
sum  total  of  which  any  one  might  be  proud. 

His  investigations  dealt  with  a  wide  variety  of  topics  and 
showed  a  steadily  increasing  desire  to  penetrate  further  into 
the  fundamental  mysteries  of  the  nature  and  mechanism  of 
chemical  reaction.  To  those  not  conversant  with  the  subject 
it  would  be  impossible  here  to  explain  the  purport  of  these 
investigations,  and  to  those  familiar  with  its  details  the 
papers  speak  for  themselves.  No  one  can  turn  the  pages 
without  the  conviction  that  this  work  was  carried  out  with 
the  earnest  desire,  which  marks  the  sincere  man  of  science, 
to  discover  the  truth  and  nothing  but  the  truth. 

Morris  Loeb's  vivid  interest  in  the  advance  of  science  did 
not  preclude  an  intelligent  appreciation  of  achievement  in 
other  fields  of  human  activity.  He  was  deeply  interested  in 
music  and  art,  and  was  one  of  the  founders  and  endowers 
of  the  Betty  Loeb  Musical  Foundation.  Himself  a  teacher 
for  years,  he  was  greatly  interested  in  all  educational  causes. 
For  several  years  he  was  a  director  of  the  Educational  Alli- 
ance, and  at  the  time  of  his  death  he  was  a  member  of  the 
Board  of  Education  of  New  York  City  and  president  of  the 
Hebrew  Technical  Institute. 


OF  MORRIS  LOEB  xxi 

On  April  3,  1895,  he  was  married  at  Cincinnati,  his  native 
city,  to  Miss  Eda  Kuhn,  who  survives  him.  After  more  than 
seventeen  years  of  devoted  married  life,  he  died  on  October 
8,  1912,  falling  a  victim  to  typhoid  fever  and  double  pneu- 
monia. He  was  a  martyr  to  his  noble  ideal  of  service;  for  one 
cannot  but  believe  that  the  way  for  his  fatal  illness  was  paved 
by  his  over-exertion  in  welcoming  at  Washington  the  mem- 
bers of  the  International  Congress.  The  interment  in  the 
family  vault  at  Salem  Fields,  Cypress  Hills,  Long  Island, 
took  place  in  the  presence  of  a  sorrowing  throng  of  men  and 
women  of  many  creeds  and  stations. 

The  esteem  in  which  he  was  held  is  manifest  in  the  many 
deeply  appreciative  resolutions  now  spread  upon  the  records 
of  the  societies  of  which  he  was  a  member.  From  among  these, 
two  are  quoted  below,  as  typical  of  the  general  recognition 
of  his  worth. 

,  At  the  meeting  of  the  Trustees  of  The  Chemists'  Club  on 
the  day  of  his  death,  the  following  preamble  and  resolution, 
drawn  up  by  Ellwood  Hendrick,  Clifford  Richardson,  and 
Walter  E.  Rowley,  were  adopted:  — 

"WHEREAS,  Morris  Loeb,  the  President  of  the  Club,  has 
been  taken  from  us  by  death;  and 

"WHEREAS,  he  was  the  leading  spirit  in  bringing  to  ful- 
fillment ambitions  and  plans  that  had  long  been  ours;  and 

"WHEREAS,  he  was  always  ready  to  shoulder  burdens  and 
to  give  help;  and 

"WHEREAS,  he  was  a  man  of  order,  and  of  integrity, 
in  mind  and  heart,  sincere  in  scholarship,  living  without 
malice  or  scorn,  speaking  no  evil,  and  generous  in  judgment; 
and 

"WHEREAS,  we  were  drawn  to  him  by  ties  of  deep  and 
abiding  affection;  now,  therefore,  be  it 

"Resolved,  that  we  make  this  minute  of  our  poignant  grief 


xxii          THE  LIFE  AND  CHARACTER 

at  his  passing,  and  that  we  cherish  his  memory  as  another  of 
his  great  gifts  to  science  and  to  humanity." 

The  following  sentences,  written  by  Marston  T.  Bogert, 
Charles  F.  Chandler,  and  William  H.  Nichols,  and  entered 
upon  the  minutes  of  the  New  York  Section  of  the  Society  of 
Chemical  Industry,  express  again  the  general  appreciation 
of  his  life  and  character:  — 

"Morris  Loeb,  chemist,  investigator,  educator,  upright 
and  useful  citizen,  altruist,  philanthropist,  generous  patron 
and  benefactor  of  art,  of  sciences,  and  of  all  good  works,  ever 
ready  to  bear  more  than  his  share  of  the  burdens  of  the  com- 
munity and  always  to  be  found  on  the  side  of  righteousness, 
justice,  and  truth,  lived  his  life  of  quiet  power  without  arro- 
gance or  display.  Always  modest  concerning  his  own  dis- 
tinguished career  and  many  accomplishments,  with  charity 
towards  all  and  unkind  criticism  of  none,  he  was  ever 
a  courteous,  genial,  and  polished  gentleman  of  high  ideals, 
whose  chief  aim  and  purpose  was  to  be  of  assistance  to  his 
fellow-men,  and  who  realized  to  the  full  that  the  highest 
reward  of  service  is  the  privilege  of  having  been  of  service. 

"Now  that  the  temporary  scaffolding  of  life  has  fallen 
away,  the  true  nobility  of  his  character  stands  clearly  revealed 
in  all  its  commanding  beauty  and  dignity,  an  imperishable 
monument  of  a  life's  work  well  done  and  a  worthy  inspiration 
to  others.  Such  manhood  is  the  real  glory  to  any  country. 
The  world  is  the  better  for  his  having  lived  in  it,  and  we  are 
the  better  for  having  known  him." 

Any  statement  of  the  good  wrought  by  this  ardent  worker 
in  the  cause  of  science  regarded  as  an  agent  for  human  ad- 
vancement would  be  incomplete  without  allusion  to  several 
of  the  provisions  of  his  will.  By  it  he  assured,  as  has  been 
already  said,  the  permanence  of  The  Chemists'  Club  as  a 


OF  MORRIS  LOEB  xxiii 

centre  of  chemical  influence  in  the  country;  he  provided  for 
the  establishment  of  a  museum  of  rare  and  typical  substances 
to  be  maintained  by  the  American  Chemical  Society;  and, 
most  important  of  all,  he  bequeathed  a  fund  of  $500,000 
to  be  used  eventually  by  Harvard  University  for  the  fur- 
therance of  the  sciences  of  chemistry  and  physics. 

These  provisions,  like  many  of  his  earlier  benefactions, 
will  bear  blessings  far  into  the  future;  the  fruit  of  his  contribu- 
tions to  the  welfare  of  humanity  will  multiply. 

In  Morris  Loeb's  life  and  character  our  country  and 
Harvard  University  have  a  right  to  take  deep  pride.  Up- 
right, unselfish,  generous,  loyal,  sincere,  wise,  and  modest,  he 
set  a  noble  example;  his  memory  is  treasured  by  all  who  had 
the  privilege  of  knowing  him.  When  those  too  have  left  this 
earthly  life,  he  will  be  kept  in  remembrance  by  his  great  gifts 
to  science  and  to  charity,  and  be  honored  by  many  generations 
in  the  years  to  come. 

THEODORE  W.  RICHARDS. 


PART  I 

LECTUBES,  ADDRESSES,  AND  REVIEWS 


THE  FUNDAMENTAL  IDEAS  OF  PHYSICAL 
CHEMISTRY1 

IN  commencing  this  course  of  lectures,  whose  subject- 
matter  and  title  are  avowedly  new  to  the  American  student, 
I  feel  the  need  of  giving  some  justification,  of  presenting 
some  reason  why  I  should  seek  to  add  one  more  round  to  the 
ladder  of  learning  already  so  alarmingly  long.  To-day,  the 
cry  against  specialization  is  increasingly  raised;  and  we  now 
and  then  hear  voices  wailing  for  the  good  old  times,  when  an 
Admirable  Crichton  could  boast  of  knowing  something  of 
all  things  knowable,  and  when  a  Pico  della  Miranqlola  could 
publish  his  readiness  to  dispute  against  all  comers,  "de 
omnibus  rebus." 

But  wishing  these  times  back  will  not  recall  them.  Loosed 
from  the  leash  of  rhetoric  and  dogmatism,  the  pursuers  of 
knowledge  have  spread  in  all  directions  over  the  field,  each 
so  eager  on  his  own  particular  trail  that  he  has  no  eye  for  the 
discoveries  of  his  neighbor;  he  forgets,  indeed,  that  there  is 
need  of  keeping  in  touch  to  the  right  and  left,  lest  important 
clues  be  passed  unobserved.  No  wonder  if  the  bewildered 
spectators  should  think  that  the  whole  pack  has  gone  mad, 
and  that  the  majority,  at  least,  have  been  diverted,  by  their 
own  self-sufficiency,  from  the  noble  quarry  upon  which  they 
had  been  set.  Nevertheless,  we  may  already  see  a  change 
in  their  methods:  they  are  shaping  their  courses  parallel  to 
each  other,  they  strive  to  keep  abreast  and  neighbors  in- 
stead of  running  apart;  they  carefully  scan  the  ground 
between  themselves,  that  nothing  may  lurk  there  unseen. 

1  Introductory  lecture  of  a  course  probably  given  at  Clark  University  in  1889. 


MORRIS  LOEB 


To  speak  in  more  sober  language,  while  it  is  still  necessary 
for  the  advancement  of  knowledge  that  investigators  should 
concentrate  their  energies  on  their  particular  fields  of  science, 
these  various  branches  are  now  approaching  so  close  together 
that  one  will  aid  the  other,  if  properly  directed.  While,  there- 
fore, it  would  be  preposterous  to  demand  of  the  anatomist 
a  full  knowledge  of  astronomy,  or  to  ask  a  geologist  for  his 
opinion  of  the  various  hypotheses  concerning  the  structure 
of  benzol,  we  may  justly  deride  the  man  who  confines  him- 
self so  closely  to  his  own  particular  hobby  that  he  remains 
ignorant  of  those  subjects  which  are  neighboring  links  in  the 
chain  of  knowledge,  merely  because  he  does  not  expect  aid 
from  them.  Such  men  may  be  most  skillful  in  delving  for 
new  facts,  they  may  light  upon  discoveries  which  will  make 
their  names  famous,  fill  their  pockets,  cover  their  breasts  with 
decorations,  and  stuff  their  cabinets  with  diplomas.  But  the 
actual  merit  of  incorporating  these  facts  into  the  world's 
knowledge  will  belong  to  him  who,  with  a  wider  view,  will 
connect  them  with  other  isolated  facts  to  form  a  harmonious 
whole. 

Especially  has  our  own  science  been  unfortunate  in  pro- 
ducing hundreds  of  specialists  of  the  narrowest  order.  The 
ever-increasing  number  of  subjects  which  claim  attention, 
the  perplexing  rapidity  with  which  new  views  supersede 
older  ones,  the  restriction  which  the  work  in  the  laboratory 
places  upon  our  time,  —  these  have  all  had  a  share  in  per- 
suading chemists  to  confine  their  attention  to  a  narrow  field 
and  to  give  scanty  hearing  to  that  which  does  not  concern 
their  own  particular  work.  But,  worse  still,  we  have  to  con- 
tend with  the  opinion  that  chemistry  is  a  practical  science, 
that  it  is  our  chief  glory  to  produce  new  compounds  of  un- 
heard-of intricacy,  that  our  recompense  is  to  be  sought  in 
some  discovery  which  will  have  a  commercial  value.  Far  be  it 


IDEAS  OF  PHYSICAL  CHEMISTRY        5 

from  me  to  detract  from  the  merits  of  a  Liebig,  a  Hofmann,  a 
Horsford,  a  Deville;  the  discoveries  by  which  they  have 
enriched  mankind  are  among  the  brightest  ornaments  of  our 
science.  But  the  brilliancy  of  their  achievements  has  so 
dazzled  the  eyes  of  the  world  as  to  lead  men  into  the  danger 
of  forgetting  that  the  true  duty  of  a  science  is  the  investiga- 
tion of  natural  phenomena,  and  that  the  employment  of 
known  forces  for  the  production  of  effects  which,  however 
novel  and  beautiful,  depend  merely  on  ingenious  combina- 
tions, must  soon  bring  chemistry  to  the  level  of  an  art.  Too 
many  chemists  hurry  in  their  studies  toward  the  El  Dorado 
of  carbon  synthesis,  striving  to  obtain  at  the  earliest  mo- 
ment tangible  results  in  the  shape  of  new  substances,  be  they 
dyes,  drugs,  or  merely  triumphs  of  synthetical  art.  In  this 
eager  chase  they  rush  heedlessly  over  the  rich  fields  of 
stoichiometry,  of  inorganic  chemistry,  of  analysis,  of  electro- 
chemistry, of  the  problems  of  chemical  affinity. 

Like  to  the  miners  of  '49  the  specialist  in  organic  chemistry 
has  but  one  thought.  Arrived  at  his  diggings,  he  delves  as- 
siduously, and  if  favored  by  fortune  and  skill  is  rewarded  with 
many  a  rich  nugget.  But  if,  resting  awhile  from  his  labors 
he  decides  to  retrace  his  steps  and  revisit  former  scenes,  he 
is  astounded  to  find  that  lands  passed  by  as  cheerless  and 
barren  have  been  occupied  by  settlers,  who  with  patience 
and  care  have  cultivated  and  beautified  them,  and  are  now 
reaping  wealth  more  lasting  and  productive  than  his  own  gold. 

Let  us,  then,  who  have  not  staked  our  claims,  travel  more 
leisurely,  tarrying  here  and  there,  surveying  our  fair  inherit- 
ance and  considering  whether  it  be  not  our  duty  to  turn  aside 
from  the  main  road,1  in  order  that  we  may  render  fruitful 
that  which  would  else  be  a  noisome  desert. 

1  In  1889  this  "main  road"  was  the  study  of  synthetic  organic  chemistry. 
[Editor.] 


6  MORRIS  LOEB 

Chemistry,  as  I  have  intimated,  owes  its  great  prominence, 
in  popular  estimation,  to  those  material  successes  of  the 
branch  called  organic  chemistry,  which  have  rapidly  suc- 
ceeded each  other  during  the  last  thirty  years.  Their  founda- 
tion was  laid  by  that  grand  work  of  systematization,  with 
which  we  find  connected  the  most  glorious  names  of  modern 
chemistry,  Liebig  and  Wohler,  Laurent  and  Gerhardt, 
Dumas,  Hofmann,  Wurtz,  Williamson,  Couper,  Kekule,  and 
Cannizzaro.  So  extensive  and  intricate  is  this  system,  and 
yet  so  fruitful  in  all  its  ramifications,  that  it  has  well  repaid 
the  intense  labor  bestowed  upon  it  by  these  men  and  the  hosts 
of  their  pupils  and  successors.  But  we  must  not  lose  sight  of 
the  fact  that,  after  the  first  successful  generalizations,  the 
work  has  been  mainly  deductive  and  not  inductive.  We  have 
had  an  algebra  devised  for  us  with  its  own  notation  and  its 
own  processes  of  reasoning:  it  remains  for  us  to  combine  these 
ingeniously,  so  that  they  may  apply  to  the  special  problems 
with  which  we  are  confronted.  Our  success  is  so  great,  that 
it  appears  that  the  propositions  upon  which  we  started  are 
axiomatic  instead  of  hypothetical,  and  general  instead  of 
special;  so  that,  when  we  have  quoted  one  of  them,  we  believe 
that  we  have  stated  the  first  principle  to  which  any  question 
can  be  referred.  As  a  matter  of  fact,  organic  chemistry  by  it- 
self only  clears  up  the  questions  of  composition  and  consti- 
tution and  of  change  within  the  molecule.  The  interesting 
problems  as  to  the  nature  of  what  we  call  atoms,  the  prop- 
erties of  the  elements,  the  peculiar  behavior  of  the  molecules 
toward  each  other,  and  —  grandest  problem  of  physical  sci- 
ence —  the  correlation  of  matter  and  energy,  do  not  present 
themselves  to  the  organic  chemist.  We  shall  have  occasion 
to  see  how  reluctant  he  is  to  accept  other  explanations  than 
those  given  by  his  formulae  for  phenomena  which  these 
formulae  seem  incapable  of  explaining  fully. 


IDEAS  OF  PHYSICAL  CHEMISTRY         7 

Turning  now  to  inorganic  chemistry,  we  find  it  completely 
overshadowed  by  its  younger  rival:  its  votaries  are  few  and 
disheartened.  I  think  that  I  do  no  injustice  in  asserting  that, 
for  most  students,  the  mention  of  this  study  conveys  no  idea 
but  that  of  laborious  quantitative  analysis  for  commercial 
and  mineralogical  purposes.  That  subdivision  which  corre- 
sponds more  closely  to  organic  chemistry,  the  description 
and  natural  history  of  the  elements  and  their  compounds,  is 
generally  taught  chemical  students  at  the  very  beginning  of 
their  course  of  study,  and  must  naturally  appear  to  be  ele- 
mentary and  of  least  importance  and  interest.  They  may 
indeed  also  recollect  dimly  some  few  introductory  lectures, 
given  as  a  necessary  evil  and  listened  to  with  imperfect  com- 
prehension, about  the  atomic  and  molecular  theories,  the  na- 
ture of  reactions  and  the  physical  properties  of  compounds, 
but  these  also  are  for  the  most  part  hidden  in  the  mists  of  the 
past. 

Do  not  understand  me  as  saying  that  all  these  subjects 
have  not  had  skillful  investigators  during  the  last  thirty  years. 
This  is  by  no  means  the  case;  we  shall  come  across  many  re- 
vered names  in  the  course  of  our  review.  The  trouble  is  that 
their  work  has  not  received  that  attention  from  the  whole 
community  of  chemists,  which  would  make  it  as  commonly 
known  as  are  the  achievements  of  organic  synthesis,  and  place 
it  upon  its  proper  pedestal  for  public  admiration.  Why  should 
we  know  less  about  silicon,  iron,  and  sulphur,  than  we  know 
about  carbon,  hydrogen,  oxygen,  and  nitrogen?  Why  should 
we  care  more  about  the  color,  melting-point,  and  boiling- 
point  of  a  compound  than  we  do  about  its  behavior  towards 
other  manifestations  of  energy  beside  light  and  heat?  Above 
all,  why  should  we  confine  ourselves  to  the  internal  consti- 
tution of  molecules,  when  we  should  also  concern  ourselves 
with  their  behavior  toward  each  other,  with  those  mysteries 


8  MORRIS  LOEB 

of  affinity  and  reaction  which  cannot  be  explained  by  merely 
paraphrasing  the  phenomena?  Not  merely  book-learning 
may  be  acquired  by  this  knowledge;  it  continually  furnishes 
us  with  new  weapons  for  the  further  investigation  of  truth. 

Gentlemen,  the  interest  in  general  and  physical  chemistry 
is  reawakening,  and  we  may  soon  hope  to  see  these  studies  as 
prominent  as  they  were  in  the  times  of  Humphry  Davy  and 
Gay-Lussac,  of  Berthollet  and  Dalton,  of  Berzelius  and  of 
Michael  Faraday.  I  am  thankful  that  this  new  university 
has  granted  me  an  opportunity  of  calling  attention  to  them 
in  our  country;  and  I  shall  be  happy  indeed  if  I  can  augment 
in  you  the  love  for  this  branch  of  speculative  philosophy, 
by  pointing  out  some  recent  achievements  and  showing  how 
much  still  remains  to  be  done. 

Confronted  with  the  necessity  of  defining  the  scope  of 
chemistry,  I  would  say:  Chemistry  is  that  branch  of  Physics 
which  treats  of  the  differentiation  of  matter.  Treading  gin- 
gerly on  the  dangerous  ground  of  metaphysics,  we  may  re- 
cognize that  there  are  four  principles  to  which  the  educated 
mind  refers  natural  phenomena,  —  four  first  causes,  four 
categories,  four  systematic  axes,  —  namely:  energy,  matter, 
space,  and  time.  The  practice  of  referring  all  outward  im- 
pressions to  these  ultimate  principles  is  undoubtedly  a  great 
advance  over  the  assumption  of  the  cruder  "elements"  of 
the  Middle  Ages,  earth,  air,  fire,  and  water;  but  even  energy, 
matter,  space,  and  time  are  not  by  any  means  ideas  to  which 
we  attach  a  definite,  unalterable  meaning.  Their  definition 
seems  to  vary  in  different  minds  and  at  different  times  in  the 
same  mind.  Some  prefer  to  consider  time  a  mode  of  space, 
and  others  consider  both  time  and  space  attributes  of  matter 
and  energy,  but  not  as  independent  essentials.  All  that  we 
can  say  of  energy  and  matter  is  that  they  exist,  at  least  to 
our  perceptions.  We  are  apt  to  consider  matter  as  some- 


IDEAS  OF  PHYSICAL  CHEMISTRY         9 

thing  more  tangible  and  material  than  energy,  but  this  is  be- 
cause we  confound  substance  with  matter.  In  fact,  we  are 
no  more  acquainted  with  matter  than  with  energy.  We  know 
matter  by  its  reaction  with  energy,  and  energy  by  its  re- 
action with  matter.  Since  one  thus  defines  and  differentiates 
the  other,  we  are  moving  in  a  vicious  circle,  and  must  pretty 
well  despair  of  reaching,  upon  physical  grounds,  a  perfect 
view  of  the  real  essence  of  either.  Matter  must,  however,  be 
defined  for  our  purposes,  and  let  us  therefore  frankly  regard 
it  as  Aristotle  did,  the  v\r}9  or  stuff,  from  which  the  Universe 
is  shaped  as  is  the  house  from  timber,  or  pottery  from  clay. 

Whether  this  ultimate  matter  is  homogeneous  or  not,  we 
have  no  means  of  knowing,  but  our  instinctive  love  of  sim- 
plification leads  us  to  suppose  that  it  is  homogeneous  and  one. 
This,  however,  is  a  purely  hypothetical  assumption.  When 
we  make  an  impartial  study  of  fact,  we  find  that  by  com- 
bining certain  portions  of  matter  with  certain  portions  of 
energy,  we  obtain  what  is  known  as  substance,  and  this  may 
appear  in  infinitely  different  forms.  It  will  seem  odd  to  you 
that  I  should  define  substance  as  a  combination  of  matter 
and  energy,  but  a  little  reflection  will  show  you  that  this  view 
is  quite  admissible.  All  substances  show  certain  qualities 
which  are  referable  to  energy,  and  may  be  considered  as  a 
combined  phenomenon  of  matter  and  energy.  Thus  we  are 
almost  unable  to  imagine  substance  without  the  energy  of 
gravitation,  of  motion,  of  chemical  affinity. 

Modern  physics  teaches  us  that  energy  is  one,  inasmuch  as 
each  form  of  energy  is  convertible  into  every  other  form,  in 
certain  definite  quantitative  ratios.  The  instinct  of  the  al- 
chemists told  them  that  all  matter  was  one,  and  each  form 
was  convertible  into  every  other  form.  If  this  were  the 
modern  aim  of  chemistry,  we  should  be  obliged  to  confess 
that  very  little  has  been  accomplished  as  yet.  We  have 


10  MORRIS  LOEB 

reached  a  class  of  about  sixty-five  substances,  which  we  have 
not  yet  been  able  to  decompose  or  transform,  and  which  we 
call  the  elements.  True,  many  chemists  believe  that  these 
elements  are  themselves  composite,  but  whether  this  is  so, 
and  whether  indeed  the  supposed  substances  of  a  more  primi- 
tive order  would  be  recognizable  by  chemical  means,  is  a 
question  which  we  are  unable  to  answer.  At  present  we  shall 
assume  that  the  chemist  recognizes  the  existence  of  different 
substances  arising  from  different  relations  between  the  hypo- 
thetical matter  par  excellence  and  the  coordinate  essence 
which  we  call  energy. 

In  all  this  attempt  to  formulate  the  essential  conditions  of 
material  existence,  the  tendency  of  our  mind  is  toward  a  sim- 
plification of  our  standards  of  reference,  —  toward  a  lessen- 
ing of  the  number  of  pigeon-holes  into  which  new  ideas  must 
be  put.  We  love  to  believe  that  the  higher  we  ascend  on  the 
scale  of  causation,  the  smaller  becomes  the  number  of  co- 
ordinate causes.  Our  experience  appears  to  justify  us  in  this 
reasoning,  and  so,  as  I  have  said,  we  have  arranged  for  our- 
selves at  that  point  where  our  experience  appears  to  stop, 
the  fiction  of  these  four  principles,  space,  time,  matter,  and 
energy.  Let  us  not  flatter  ourselves,  however,  that  this  is  an 
achievement  of  modern  physics.  The  speculations  of  philos- 
ophers long  ago  led  them  to  the  same  physical  conceptions, 
and  if  Aristotle's  elements  appear  grosser  to  us,  it  is  because 
we  have  stripped  off,  as  unessential,  some  of  the  accessory 
qualities  with  which  he  had  clothed  the  mathematical  skele- 
ton. Struggle  as  we  may,  we  cannot  rid  our  own  few  prin- 
ciples of  some  quality  in  common  and  consequently  ulterior: 
above  all  things  we  give  them  alike  that  vague,  awesome  at- 
tribute of  existence:  essences,  let  us  call  them,  because  they 
appear  to  us  to  be  the  ultimate  things  that  exist,  according 
to  our  mundane  imagination.  All  that  we  tell  ourselves  is, 


IDEAS  OF  PHYSICAL  CHEMISTRY       11 

that  we  can  ascribe  all  the  phenomena  which  we  see  to  the 
combination  of  these  essential  principles,  of  whose  nature 
we  know  nothing,  and  which  are,  consequently,  infinite  to  us. 
This  does  not  preclude  our  singling  out  finite  portions  of 
these,  so  to  speak,  and  defining  them  by  each  other. 

We  have  seen  that  we  are  not  justified  in  calling  substance 
a  manifestation  of  matter  free  of  energy:  it  is  so  intimately 
connected  with  certain  forces  (such  as  gravitation)  which  are 
convertible  into  so-called  manifestations  of  pure  energy, 
that  we  cannot  conceive  of  it  as  existing  deprived  of  these, 
and  yet  remaining  recognizable.  But  we  may  neverthe- 
less class  all  substances  together  in  one  general  class  called 
matter. 

Thus  also,  the  various  modes  of  energy  —  heat,  motion, 
electricity,  chemical  affinity  —  are  phenomena  which  we 
dare  not  ascribe  to  energy  alone,  for  we  cannot  conceive  them 
as  separated  from  matter.  We  can,  therefore,  speak  of  their 
differentiation  also,  although  we  may  picture  the  tran- 
scendental energy  as  one  and  homogeneous.  Indeed,  con- 
sciously or  unconsciously,  this  distinction  is  made  in  the 
science  of  thermodynamics,  which  proposes  to  treat  energy 
in  its  abstractest  form.  .  .  . 

In  view  of  these  philosophical  complications,  I  propose 
that  we  do  not  allow  ourselves  to  be  hampered  by  metaphys- 
ical notions  as  to  the  respective  homogeneity  of  matter  and 
energy,  but  that  we  accept  frankly,  at  the  outset,  the  appear- 
ance of  substances  and  forces  in  various  distinct  forms. 
Physical  research  will  show  us  that  there  exist  between  all 
these  forms  certain  relations,  about  which  it  is  our  duty  to 
procure  definite  ideas.  If  the  advance  of  knowledge  shall 
gratify  our  love  of  symmetry,  by  proving  that  the  correla- 
tions of  the  various  forms  may  be  traced  to  the  existence  of  a 
simpler  set  of  relations,  of  a  higher  order,  well  and  good !  But 


12  MORRIS  LOEB 

let  us  not  allow  our  feelings  to  warp  our  judgment,  or  a  priori 
reasoning  to  mislead  our  investigations. 

Of  the  various  properties  by  which  we  recognize  substance, 
there  are  some  which  are  necessary  concomitants  of  the  very 
existence  of  matter,  —  which  appear  to  accompany  matter 
so  faithfully,  that  no  particle  can  boast  of  holding  much  more 
than  another.  Among  these  we  reckon  extent,  impermeability, 
mobility,  gravitation,  inertia.  .  .  . 

Then  there  are  other  properties  which  we  do  not  hesitate 
to  term  accidental;  they  are  so  loosely  connected  with  the 
substances  that  we  do  not  recognize  the  substances  as  dis- 
similar on  that  account.  They  might  more  properly  be  ap- 
plied to  the  differentiation  of  energy.  Such  properties  are 
position,  temperature,  electrical  or  magnetic  change.  They, 
indeed,  may  appear  on  one  body  more  than  on  the  other;  but 
exchange  the  proportionate  quantities  in  the  two  bodies,  as 
well  as  we  may,  and  yet  we  shall  not  be  likely  to  confound  one 
body  with  the  other.  These  are  all  transferable  properties, 
the  one  body  gaining  what  the  other  loses. 

There  are,  however,  yet  other  properties,  more  or  less 
concerned  with  the  foregoing,  which  two  bodies  may  not 
possess  in  like  degree,  and  which  it  is  impossible  for  one  body 
to  convey  to  the  other.  Substances  differ  in  their  behavior 
toward  the  same  form  of  energy  or  toward  each  other,  in 
the  distribution  of  their  mass  in  space  (specific  gravity),  in 
their  effect  upon  our  senses,  and  upon  the  animate  organism 
in  general.  These  properties  cannot  be  transferred  from  one 
body  to  another;  but  one  substance  may  modify  by  its  pres- 
ence the  properties  of  another.  Such  are  the  properties 
which  really  distinguish  the  different  forms  of  matter,  and  it 
is  with  these  that  chemistry  has  to  do. 

The  indivisible  unit  for  the  chemist  is  to  be  found  in  the 
homogeneous  substance;  beyond  this  he  must  confess  that 


IDEAS  OF  PHYSICAL  CHEMISTRY       13 

he  cannot  go.  As  soon  as  he  has  found  something  in  which 
he  can  detect  nothing  heterogeneous,  which  he  is  unable  by 
any  known  means  to  divide,  he  stops  at  what  he  calls  the 
elementary  atom. 

You  will  notice  that  this  is  by  no  means  a  positive  defi- 
nition by  which  we  deny  to  our  imagination  the  right  of 
subdividing  our  atom  or  of  dissociating  our  element.  We 
merely  ask  for  better  proof  than  that  of  instinct,  before  we 
allow  the  inferences  that  are  to  be  drawn  from  such  a  further 
subdivision  to  affect  our  treatment  of  the  subject.  The  testi- 
mony which  we  present  in  favor  of  the  homogeneity  of  our 
ultimate  element  is  purely  negative:  we  have  found  no  hetero- 
geneity. For  example,  we  take  this  piece  of  rock;  to  the 
geologist,  it  presents  itself  as  a  unit,  granite.  The  lithologist 
sees  in  it  a  composite  mass  of  quartz,  feldspar,  and  mica, 
which  again  are  individuals  for  his  eye.  But  for  the  chemist, 
feldspar  is  highly  complex:  he  can  isolate  from  it,  silicon, 
oxygen,  potassium,  aluminium,  magnesium,  iron,  and  possi- 
bly other  elements.  No  means  have  yet  been  devised  so 
subtle  as  to  subdivide  these  elementary  substances. 

Recognizing  such  as  our  simple  substances,  we  find  that 
each  has  certain  properties  of  its  own,  which  serve  to  dis- 
tinguish it  from  the  rest,  and  which  cannot  be  transferred 
from  it  to  one  of  its  fellows.  The  ancient  and  mediaeval 
alchemists  regarded  these  elements  as  composites,  contain- 
ing in  different  proportions  those  principles  of  Aristotle  to 
which  we  have  already  referred.  To  them,  therefore,  it 
seemed  perfectly  logical,  that  by  addition  or  subtraction  of 
some  quality-bearing  principle,  one  metal  could  be  converted 
into  another.  It  is  only  because  we  have,  by  carefully  con- 
ducted experiments,  found  the  metals  to  be  homogeneous, 
toward  all  the  agencies  which  we  know,  —  that  we  have  come 
to  another  conclusion,  and  ridicule  the  idea  of  their  mutation. 


14  MORRIS  LOEB 

Their  reasoning  appeared  to  them  to  be  as  logical  as  ours  is, 
when  we  propose  transforming  the  sap  of  the  pine  into  the 
essence  of  vanilla,  or  of  converting  clay  into  the  true  ruby. 

As  I  have  said,  we  recognize  upwards  of  sixty-five  elements, 
but  we  rarely  see  any  of  these  pure.  Terrestrial  objects  must, 
then,  be  made  up  of  combinations  of  these  elements.  In 
order  to  study  them  in  the  pure  state,  they  must  usually  be 
separated  from  each  other;  and  they  are  worthy  of  very  care- 
ful study.1  .  .  . 

You  are  aware  of  the  Periodic  Law  of  Newlands,  Lothar 
Meyer,  and  Mendeleeff,  which  traces  such  remarkable  re- 
lations between  the  various  properties  of  the  elementary 
substances  and  the  relative  masses  of  their  imaginary  atoms. 
Attempts  to  connect  this  law  with  the  idea  that  the  elements 
are  compounds  in  a  chemical  sense  are  abortive.  I  believe 
that  the  law  can  be  more  readily  traced  to  the  relation  of  the 
quantities  in  which  our  fundamental  ideas  of  matter,  energy, 
and  space  are  associated  for  each  element.  The  atoms  of  the 
elements  have  undoubtedly  different  densities.  That  is  to 
say,  our  knowledge  of  the  sizes  of  the  atoms,  limited  though 
it  be,  does  not  allow  us  to  suppose  that  an  oxygen  atom  occu- 
pies sixteen  times  the  volume  which  a  hydrogen  atom  requires, 
although  this  is  the  ratio  of  the  masses  of  these  two  kinds  of 
atoms.  For  the  same  amount  of  space  there  seems  to  be  more 
matter  in  the  oxygen  atom  than  in  the  hydrogen  atom;  we 
may  assume  that  similar  relations  exist  in  other  cases  with 
regard  to  energy  and  matter.  For  each  element  we  should  have 
to  assume  new  quantities  of  matter,  space,  and  energy;  and 
the  ratios  of  every  one  of  the  three  with  respect  to  each  other 
would  vary.  We  might  suppose,  however,  that  for  a  series 
of  elements  the  ratio  of  two  of  the  fundamental  quantities 

1  The  lecture  notes  on  physical  chemistry  here  became  fragmentary.  The  fol- 
lowing six  pages  were  taken  from  two  summaries  evidently  prepared  for  addresses 
on  other  occasions.  [EDITOR.] 


IDEAS  OF  PHYSICAL  CHEMISTRY       15 

remained  fixed,  but  their  ratio  toward  the  third  varied;  in 
such  cases  we  might  expect  marked  similarity  in  their  proper- 
ties, as  compared  with  those  cases  where  all  the  ratios  varied. 
Such  reasoning,  carried  out  more  fully,  might  explain  the 
peculiarities  of  the  Periodic  Law,  even  though  this  does  not 
necessarily  imply  that  no  other  explanation  is  possible. 

Even  if  we  do  not  altogether  understand  the  relations 
between  the  elements,  our  chemical  theory  concerning  the 
nature  of  these  elementary  substances  is  very  simple.  Assum- 
ing the  elements  to  exist,  each  element  is  represented  by  one 
set  of  extremely  small  indivisible  atoms,  the  atoms  of  the 
same  element  being  exactly  alike  in  all  respects.  They  are 
independent  bodies  exerting  upon  other  atoms  an  attraction 
which  varies  according  to  their  nature.  .  .  . 

These  atoms  are  supposed  to  unite  into  small  clusters  that 
we  call  molecules,  and  consider  as  the  smallest  independent 
bodies  that  have  the  properties  of  ordinary  tangible  sub- 
stances. They  remind  us  strongly  of  planetary  systems,  like 
our  solar  systems,  because  they  execute  their  own  movements 
quite  independently  of  the  movements  of  their  constituent 
atoms.  The  molecules  present  comparatively  easy  problems 
to  the  theorist;  their  own  motions  seem  to  be  simple  and  their 
mutual  attractions  are  at  least  in  part  those  of  gravitation. 
The  so-called  "kinetic  theory  of  gases"  explains  all  phenom- 
ena of  the  gaseous  state  very  readily  by  assuming  that 
molecules  move  in  straight  lines  until  they  hit  an  obstacle  and 
are  then  reflected.  If  molecules  come  very  close  to  one  an- 
other, their  relative  attraction  becomes  much  greater  than 
that  which  corresponds  to  gravitation.  I  think  it  fair  to  as- 
sume that  then  their  more  complex  chemical  attractions 
come  into  play. 

Thus  our  chemical  philosophy  becomes  an  attempt  to  inter- 
pret the  actions  of  these  imaginary  atoms  constituting  matter 


16  MORRIS  LOEB 

under  the  play  of  the  various  forms  of  energy  which  pertain 
to  them;  and  these  actions  must  be  supposed  to  take  place 
in  tridimensional  space  during  perceptible  time. 

Let  us  turn  now  to  the  consideration  of  energy.  We  talk 
of  kinetic  energy,  or  energy  performing  work,  and  of  poten- 
tial energy,  or  energy  which  is  capable  of  performing  work, 
but  not  yet  doing  so.  In  the  case  of  the  mechanical  energy 
of  motion,  the  potential  form  involves  change  in  time  but  not 
in  other  obvious  ways.  It  keeps  on  existing  in  the  shape  of 
a  tendency  to  move,  attraction  or  the  like,  while  the  kinetic 
form  involves  both  a  change  in  respect  to  time  and  to  the 
directions  of  space.  We  recognize  this  in  the  word  speed, 
or  velocity,  which  expresses  the  distance  traversed  in  com- 
parison with  the  amount  of  time  consumed.  I  think  this 
energy  of  motion  to  be  the  easiest  to  conceive,  and  conse- 
quently the  most  natural  to  imagine  as  at  the  bottom  of  all 
phenomena  of  energy.  Certain  it  is  that  physicists  are  finding 
more  and  more  reason  to  believe  that  all  the  various  forms 
of  energy  are  really  only  manifestations  of  different  sorts  of 
direct  motion. 

For  example,  we  find  that  what  we  know  as  heat  or  light 
may  be  simply  interpreted  as  a  manifestation  of  the  motions 
of  the  molecules.  If  we  heat  a  substance,  its  molecules  may 
be  supposed  to  move  more  rapidly  in  straight  lines  and  vi- 
brate or  oscillate  more  rapidly.  The  oscillations  they  are  able 
to  impart  to  neighboring  particles  that  may  be  incapacitated 
from  directly  taking  up  the  rectilinear  motions.  If  these  mo- 
tions or  oscillations  are  very  rapid,  they  affect  our  sense  of 
temperature.  They  may  partly  belong  to  the  molecule  as  a 
whole,  partly  to  its  atoms. 

All  sorts  of  molecules  may  be  supposed  to  receive  the  straight 
motions  in  equal  degree;  but  each  molecule  seems  to  respond 
only  to  certain  kinds  of  oscillations.  So  we  can  throw  a  set 


IDEAS  OF  PHYSICAL   CHEMISTRY       17 

of  bells  an  equal  distance  at  the  same  speed;  but  each  bell  has 
its  own  rates  of  vibration,  its  tones  and  over-tones.  You  know 
that  in  light  and  heat  vibrations,  the  colors  of  the  spectro- 
scope are  due  to  the  preference  which  molecules  exhibit  for 
certain  rates  of  vibration.  .  .  . 

What  now  are  the  forms  of  energy  concerned  in  causing 
chemical  action?  Until  recently  the  chemist  has  dealt  with 
static  chemistry,  —  that  is,  the  science  in  which  the  proper- 
ties of  quiescent  substances  are  discussed,  —  rather  than  with 
the  branch  of  knowledge  which  discusses  the  mechanism  of 
chemical  change.  Whenever  affinity  is  treated  as  a  specific 
inherent  property  of  the  atoms,  we  naturally  adopt  the  old- 
fashioned  views  first  enunciated  by  Bergmann  more  than  a 
century  ago,  that  elements  unite  according  to  their  specific 
affinity  for  each  other.  If  two  substances  are  presented  to  a 
third  which  would  combine  with  either  of  them,  it  was  sup- 
posed to  take  up  the  one  for  which  it  had  the  greater  affinity, 
leaving  the  other  uncombined.  This  doctrine  of  elective  affini- 
ties is  a  comfortable,  but  unfortunately  an  incomplete  one. 
It  represents  only  one  side  of  the  question. 

If  we  continue  building  upon  the  kinetic  theory  discussed 
above,  a  more  complicated  process  is  to  be  expected.  As  a 
matter  of  fact  we  find  that  substances  act  upon  each  other 
not  only  according  to  their  mutual  affinity,  but  are  also 
influenced  by  such  conditions  as  their  relative  quantities  in  a 
given  space,  their  temperature,  etc.  To  illustrate  the  former 
of  these  two  circumstances,  suppose  a  mixture  of  equal  masses 
of  A  and  B,  which  do  not  act  upon  each  other,  to  be  pre- 
sented to  C,  with  which  both  can  react,  but  A  more  readily 
than  B.  A  and  C  will  unite,  but  not  to  the  exclusion  of  B; 
there  will  be  a  partition  of  C  between  A  and  B,  in  which 
A,  the  more  active,  gets  the  greater  share  of  C.  When,  how- 
ever, the  quantity  of  B  originally  present  is  increased,  more  of 


18  MORRIS  LOEB 

C  will  combine  with  B  than  would  originally  combine  with  it. 
This  is  due  to  the  fact  that  chemical  action  is  due  to  exchange 
of  atoms  when  molecules  meet.  In  spite  of  some  reluctance 
to  combine  between  B  and  C,  the  greater  number  of  mole- 
cules of  B  present  causes  more  frequent  meetings  between 
B  and  C  atoms  than  between  A  and  C  atoms.  Throughout 
chemical  reactions  it  is  found  to  be  true  that  the  ultimate 
result  depends  thus  upon  the  relative  concentrations  of  re- 
agents quite  as  much  as  upon  their  affinity.  This  then  is  a 
second  aspect  of  the  science  of  energetics  which  applies  to 
chemical  action. 

Formerly  the  chemist  measured  or  weighed  the  substances 
which  he  put  together;  and  then  measured  and  weighed  the 
ultimate  results,  wrote  an  equation  and  heaved  a  sigh  of 
satisfaction  at  having  mastered  the  mechanism  of  the  reac- 
tion. Since  the  ideas  above  related  have  been  introduced,  we 
strive  to  follow  the  reaction  while  it  is  going  on,  to  detect 
the  molecules  at  work.  We  must  often  devise  special  methods 
for  such  a  purpose  and  many  difficulties  have  hitherto  seemed 
unsurmountable.  But  when  we  do  obtain  such  glimpses,  we 
become  more  and  more  convinced  of  the  fewness  and  sim- 
plicity of  the  fundamental  ideas  which  we  require  for  a  basis 
of  the  science. 

In  any  simple  reaction,  there  is  a  perceptible  interval  of 
time  between  the  mixture  of  the  ingredients  and  the  com- 
pletion of  the  ultimate  result.  Why  is  this?  Because  a 
measurable  interval  elapses  before  all  the  molecular  changes 
have  taken  place.  This  will  depend,  as  pointed  out  above, 
first  upon  the  readiness  with  which  the  exchange  takes  place 
(a  question  of  affinity),  secondly  upon  the  frequency  of  meet- 
ing of  the  reacting  molecules.  Molecules  will  meet  more 
freely  if  there  are  more  of  them  in  a  given  space,  and  if  they 
move  faster  through  added  energy;  and  colliding  molecules  of 


IDEAS  OF  PHYSICAL  CHEMISTRY       19 

the  two  reacting  substances  will  combine  more  frequently, 
the  greater  their  mutual  affinities.  This  relation  of  chemical 
change  to  time  is  one  of  the  most  important  aspects  of  modern 
physical  chemistry.1 

In  recent  years  it  has  become  possible  to  produce  an  in- 
tense cold,  and  it  has  been  observed  in  the  laboratories  of  Pro- 
fessor Dewar  and  others,  that  as  the  temperature  decreases, 
the  speed  of  reaction  also  decreases.  Furthermore,  it  has  long 
been  known  that  matter  usually  contracts,  that  is  to  say, 
occupies  less  space,  as  it  grows  colder.  At  a  temperature 
minus  273°  centigrade,  all  heat  energy  ceases,  all  chemical 
reactions  become  exceedingly  slow,  and  all  volume  approaches 
as  near  as  possible  to  nothing  without  the  actual  disappear- 
ance of  substance.  It  is  fair  to  assume  that  at  such  an  abso- 
lute zero  various  other  properties  by  means  of  which  we  dif- 
ferentiate substances  would  disappear,  and  this,  too,  is  veri- 
fied by  recent  observations.  Nevertheless,  all  substances 
by  no  means  become  identical  at  this  point.  Because  heat  is 
a  form  of  energy,  and  cold  is  only  the  absence  of  that  form 
of  energy,  we  have  here  only  another  aspect  of  the  ever-re- 
curring effect  of  the  changing  relation  of  matter  to  energy 
in  producing  the  phenomena  of  our  actual  world. 

In  summing  up  the  outcome  of  our  work  in  this  lecture, 
it  is  clear  that  we  have  built  a  sort  of  platform,  floating  upon 
a  sea  of  uncertainty,  but  of  sufficient  strength  and  stability 
to  permit  the  erection  of  a  more  solid  edifice  of  physico-chemi- 
cal theory.  Let  us  cast  another  glance  at  the  planks.  We  have 
the  four  fundamental  ideas,  matter,  energy,  space  and  time 
-  which  occur  in  everything  superposed  upon  one  another 
but  not  in  a  constant  quantitative  ratio;  these  abstract  es- 

1  An  experiment  demonstrating  the  effect  of  concentration  and  temperature 
upon  the  speed  of  reaction  is  given  at  the  end  of  the  Appendix  to  this  volume. 
[Editor.] 


20  MORRIS  LOEB 

sences  cooperate  in  the  manifestation  of  chemical  substances, 
of  kinetic  energy  of  motion,  and  of  potential  energy  of  posi- 
tion. I  think  that  you  will  agree  with  me  that  although  we 
may  not  be  generally  aware  of  it,  these  four  fundamental 
conceptions  work  together  in  our  minds  and  our  senses  in 
producing  all  our  perceptions  of  the  chemical  phenomena  of 
nature. 


OSMOTIC  PRESSURE  AND  THE  DETERMINA- 
TION OF  MOLECULAR  WEIGHTS1 

WITHIN  recent  years  it  has  become  more  and  more  appar- 
ent that  an  intimate  connection  exists  between  the  stoichio- 
metrical  composition  of  a  solution  and  its  physical  behavior. 
While  earlier  efforts  towards  proving  this  assumption  were 
unsuccessful,  chiefly  because  the  experimental  material  was 
almost  wholly  confined  to  aqueous  solutions  of  salts,  which 
offer  peculiar  obstacles  to  such  an  investigation,  F.  Raoult's  2 
patient  researches  upon  organic  substances  in  more  varied 
solutions  have  enabled  him  to  formulate  accurately  the  long- 
expected  laws,  and  to  put  the  chemical  world  under  lasting 
obligation  for  new  methods  for  determining  molecular 
weights  under  very  favorable  conditions.  Raoult's  law  would 
read,  in  its  most  general  form :  In  dilute  solutions  the  depres- 
sions of  the  vapor  tension  and  of  the  freezing-point  of  the 
solvent  vary  directly  with  the  ratio  between  the  numbers  of 
molecules  of  solvent  and  of  substance  dissolved  in  the  mix- 
ture. Provided  there  be  no  chemical  action  involved  in  the 
process  of  solution,  this  relation  is  entirely  independent  of 
the  nature  of  the  substances. 

Within  the  ordinary  range  of  conditions,  the  freezing-point 
of  a  pure  liquid  is  constant;  according  to  Raoult's  law,  every 
molecule  of  foreign  matter  occasions  the  same  constant  de- 
pression. Every  liquid,  however,  has  its  own  constant  coeffi- 
cient of  depression,  which  may  be  found  by  determining  the 
depression  caused  by  the  presence  of  one  molecule  of  any 
substance  in  one  hundred  molecules  of  the  liquid. 

1  A  brief  review  of  preceding  work  published  in  the  American  Chemical  Journal, 
12,  130  (1890). 

2  Campt.  rend.  87,  167  (1878);  95,  1030  (1882). 


22  MORRIS  LOEB 

The  vapor  tension  of  a  liquid  is  not  constant  within  the 
range  of  ordinary  experimentation,  since  it  is  a  complex  func- 
tion of  the  temperature  and  of  the  nature  of  the  substance. 
But  Raoult  has  shown  that  its  depression  shows  a  relation 
to  percentage  of  foreign  molecules  which  is  independent  of 
temperature,  provided  he  expresses  the  depression,  not  in 
absolute  measure,  but  as  a  fraction  of  the  tension  of  the  pure 
solvent  at  the  same  temperature.  Then  the  molecular  de- 
pression, i.e.,  the  product  of  the  molecular  weight  of  the  sub- 
stance dissolved  into  the  relative  depression  of  a  one  per 
cent  solution,  becomes  a  definite  constant  for  any  substances 
which  that  particular  liquid  may  dissolve.  It  is  noticeable 
that  this  constant's  numerical  value  always  approaches  very 
nearly  -j^  of  the  molecular  weight  of  the  solvent.  The  con- 
stant is  therefore  likewise  independent  of  the  nature  of  the 
solvent;  one  may  generalize  for  all  solutions,  that  the  ten- 
sion of  the  pure  solvent  is  to  the  actual  depression  as  is  the 
number  of  molecules  of  solvent  to  the  number  of  molecules  of 
substance  dissolved. 

Laws  as  simple  as  these  point  to  conditions,  in  solutions, 
very  like  those  existing  in  the  gaseous  state.  How  great  this 
analogy  is  has  been  shown  in  the  well-matured  papers  of  J.  H. 
van  't  Hoff  1  on  osmotic  pressure.  Osmotic  pressure  is  the 
name  given  by  van  't  Hoff  to  the  force  with  which  a  liquid 
will  enter  into  a  cell  containing  the  solution  of  some  sub- 
stance in  that  liquid  through  walls  which  are  pervious  to  the 
solvent  alone.  Pfeffer2  has  shown  that  when  such  a  cell  is 
put  into  a  vessel  containing  the  pure  solvent,  the  latter  will 
enter  the  cell,  increasing  the  bulk  of  the  solution  within,  until 
this  tendency  is  counterbalanced  by  the  difference  of  level 
in  the  two  vessels  or  some  other  pressure.  The  pressure 

'  Z.  physik.  Chem.  1,  481  (1887). 

*  Monograph,  Osmotische  Untersuchungen.  Leipzig,  1877. 


OSMOTIC  PRESSURE  23 

required  to  counterbalance  this  tendency  toward  endosmose 
is  always  the  same  for  the  same  concentration  of  the  solu- 
tion, and  for  different  concentrations  is  found  to  be  propor- 
tionate to  the  number  of  molecules  dissolved  in  the  unit 
volume.  Whether  this  osmotic  pressure  be  due  to  the  motions 
of  the  dissolved  molecules  or  to  the  attraction  of  some  other 
sort  which  they  exert  upon  the  solvent,  it  is  evident  that 
the  effect  must  depend  upon  the  number  of  molecules  per 
unit  volume  only  when  the  molecules  of  the  dissolved  body 
are  free  to  act  independently  of  each  other,  as  do  the  mole- 
cules of  a  gas.  What  the  real  kinetic  energy  of  the  molecules 
in  such  a  solution  is,  we  do  not  decide  by  drawing  this  con- 
clusion. Even  if  it  be  as  great  as  in  a  gas,  the  great  resist- 
ance which  a  solvent  opposes  to  diffusion  shows  that  there 
is  a  force  which  greatly  diminishes  the  external  effect  of  this 
kinetic  energy;  it  can  never,  therefore,  have  occurred  to 
van  't  Hoff  to  claim  that  osmotic  pressure  is  to  be  measured 
externally  in  the  same  absolute  unit  as  gaseous  pressure. 
But  this  opinion  seems  to  have  gained  a  foothold,  so  that 
the  kinetic  treatment  of  the  subject  is  combated  by  M. 
Pupin,1  on  the  ground  that  the  kinetic  energy  of  the  mole- 
cules in  a  solution  ought  to  burst  the  containing  vessel  when 
it  was  concentrated  to  what  would  correspond,  in  the  gaseous 
state,  to  a  volume  under  the  pressure  of  many  atmospheres. 
For  this  reason  he  demands  that  osmotic  pressure  should  be 
treated  as  a  static  phenomenon.  To  the  writer,  Dr.  Pupin 
appears  to  confound  molar  and  molecular  kinetics.  Because 
the  mass  as  a  whole  is  in  equilibrium  and  at  rest,  it  does  not 
follow  that  the  molecules  must  be;  in  fact  very  few  physicists 
would  care  to  call  any  force  static  in  the  sense  that  it  was 
not  occasioned  by  kinetic  forces  held  in  equilibrium  for  the 
moment. 

1  Dissertation,  Der  osmotische  Druck,  etc.,  University  of  Berlin,  1889. 


24  MORRIS  LOEB 

That  the  vessel  is  not  exploded  by  the  pressure  of  the 
molecules,  as  Dr.  Pupin  demands,  is  due  to  the  same  force 
of  solution  which  prevents  their  evaporating  at  the  free  sur- 
face. How  great  this  force  can  become  we  may  guess  from  the 
enormous  condensation  taking  place  in  the  absorption  of 
gases  by  liquids;  that  the  force  is  a  kinetic  one  is  shown  by 
its  being  a  function  of  temperature,  a  purely  kinetic  phenom- 
enon. Bredig1  has  recently  endeavored  to  show  how  this 
force  can  be  made  to  diminish  the  external  effect  of  the 
kinetic  energy  of  the  molecules  of  dissolved  substance  in 
such  a  manner  that  there  is  still  freedom  of  action  within  the 
mass;  and  upon  this  line  of  reasoning  we  must  depend  for  a 
final  explanation  of  the  phenomena. 

For  van  't  Hoff  it  was,  however,  sufficient  that  an  osmotic 
pressure  does  exist  which  is  dependent  upon  the  kinetic 
energy  of  the  molecules.  By  simple  application  of  the 
method  of  Carnot's  cycle,  he  shows  that  the  osmotic  pressure 
must  be  proportional  to  the  absolute  temperature,  and  that, 
for  solutions  of  gases,  it  corresponds  precisely  to  the  tension 
of  the  gas  in  the  solution.  A  natural  inference  from  all  this 
is  that  Boyle's,  Gay-Lussac's,  Henry's,  and  Avogadro's  laws 
find  their  counterparts  in  the  laws  governing  osmotic  pres- 
sure. 

Suppose  now  solutions  of  two  different  substances  in  the 
same  solvent  to  possess  the  same  tension  for  the  vapor  of 
the  latter;  it  is  necessary  that  they  shall  also  have  the  same 
osmotic  pressure.  For  suppose  them  separated  by  a  wall 
which  is  permeable  to  the  solvent  alone,  but  with  their  free 
surfaces  in  communication  through  the  atmosphere.  The 
vapor  tension  of  both  being  the  same,  a  little  of  the  solvent 
might  distill  from  one  solution  to  the  other  without  the  per- 
formance of  any  work;  but  if  at  the  same  time  their  osmotic 
1  Z.  phydk.  Chem.  4,  444  (1889). 


OSMOTIC  PRESSURE  25 

pressure  were  different,  work  would  be  performed  by  the  re- 
transfer  of  the  same  quantity  of  solvent  through  the  mem- 
branous wall;  this  would  mean  a  continuous  process  in  an 
isolated  system,  attended  by  gain  or  loss  of  energy.  As  this 
is  impossible,  equal  vapor  tension  means  equal  osmotic  pres- 
sure, and  vice  versa.  Consequently  the  same  number  of 
molecules  always  produce  the  same  depression  of  vapor 
tension  in  a  solvent.  Exactly  the  same  sort  of  reasoning 
would  show  that  solutions  having  the  same  freezing-point 
have  like  osmotic  pressures.  Both  of  these  laws  are  identical 
with  those  found  empirically  by  Raoult.  Thermodynamic 
reasoning  further  shows  that  the  molecular  depression  of 
vapor  tension  is  indeed  one  hundredth  of  the  molecular  weight 
of  the  solvent,  while  the  depression  of  the  freezing-point 

depends  more  directly  upon  the  nature  of  the  solvent,  being 

TZ 
a  function  of  its  latent  heat  of  liquefaction:  £=0.02— » where 

T  is  the  absolute  temperature  of  congelation  of  the  pure  sol- 
vent, W  is  the  latent  heat  per  kilogram,  and  t  is  the  molec- 
ular depression. 

These  are  the  main  results  of  van  't  Hoff 's  deductions,  as 
far  as  molecular  weight  determinations  are  concerned.  They 
enable  us  to  employ  for  this  purpose,  with  perfect  confidence, 
observations  upon  the  phenomena  of  evaporation,  freezing, 
and  osmose. 

The  direct  measurement  of  osmotic  pressure,  as  was  done 
by  Pfeffer,  is  difficult  and  not  universally  feasible.  On  the 
other  hand,  de  Vries  has  shown  how  to  compare  such  pres- 
sures by  means  of  plant  cells.1  It  is  found  that  the  living  pro- 

1  Pringsheim's  Jahrbucher  fur  Wissenschaftl.  Botanik,  14,  4.  See  also  Z.  physik. 
Chem.  2,414  (1888).  Bonders  and  Hamburger  have  shown  that  the  same  phenom- 
ena can  be  studied  in  the  behavior  of  blood-corpuscles;  Archiv.  fiir  Anatomic  und 
Physiologic,  Physiolog.  Abth.  1886,  476,  also  Hamburger,  Maanbl.  Nat.  Wetensch. 
1889,  63. 


26  MORRIS  LOEB 

toplasm  of  such  cells,  placed  in  a  solution  whose  solvent  only 
can  penetrate  the  membrane,  will  yield  water  to  the  solution 
if  the  latter  be  concentrated,  while  it  will  take  it  up  again  if 
the  solution  be  diluted.  The  protoplasm  will  therefore  re- 
cede from  the  walls  of  its  cell,  or  again  approach  it,  and  this 
expansion  or  contraction  can  be  observed  with  the  micro- 
scope. By  systematic  dilution,  a  point  may  be  determined 
for  every  substance  where  it  is  isotonic  with  another,  i.e.,  will 
neither  expand  nor  contract  a  protoplasm  which  had  come 
to  rest  in  the  other.  Interesting  as  this  method  is,  and  ca- 
pable of  yielding  good  results  in  the  hands  of  a  skillful  micro- 
scopist,  it  is  hardly  useful  in  the  chemical  laboratory,  where, 
aside  from  lack  of  familiarity  with  microscopic  work,  the 
investigator  would  be  hampered  by  the  exclusion  of  all 
substances  which  will  kill  plant  life. 

The  freezing-point  method  has  recently  been  reviewed  in 
this  magazine;  it  therefore  only  remains  for  the  writer  to 
express  his  view  of  its  scope.  While  originally  only  those  few 
liquids  were  used  as  solvents  whose  freezing-points  approached 
that  of  water,  recent  investigators  have  successfully  em- 
ployed substances  like  paraffine  and  the  more  fusible  metals 
as  the  solvent;  there  are,  therefore,  few  substances  which  are 
not  amenable  to  the  method.  But  the  following  errors  should 
be  avoided:  the  use  of  thermometers  not  sufficiently  sensi- 
tive to  admit  of  observations  at  high  dilutions;  contenting 
one's  self  with  observations  within  too  limited  a  range  of  con- 
centration to  exclude  a  chance  of  overlooking  abnormal  be- 
havior at  some  point;  allowing  too  great  a  change  of  concen- 
tration to  occur  through  the  separation  of  the  solvent  in  the 
solid  state;  using  solvents  which  have  a  chemical  effect  upon 
the  substance  under  investigation.  Substances  dissociate  in 
one  liquid  which  remain  in  complexer  molecules  in  another. 
Chemists,  in  applying  Raoult's  methods,  must  remember 


OSMOTIC  PRESSURE  37 

that  all  electrolytes  behave  abnormally  in  aqueous  solutions* 
and  that  the  presence  of  hydrates  may  affect  the  result. 

The  method  of  determining  the  molecular  weight  from  the 
vapor  tension  of  the  solution  is  not  yet  applied  so  generally; 
but  its  scope  is  even  greater,  because  the  range  of  solvents  and 
of  temperatures  is  so  largely  increased.  Raoult  and  Planck1 
have  shown  independently  of  each  other  that  the  formula 
for  the  molecular  weight  of  the  dissolved  substance  is 


where  M  0  is  the  molecular  weight  of  the  solvent,  p  the  per- 
centage of  substance  in  100  grams  of  solvent,  /  and  /'  the 
tensions  of  the  pure  solvent  and  the  solution  respectively. 

Raoult  measures  /  and  /'  by  the  heights  of  the  mercury  in 
eudiometers  containing  the  liquids.  A  knowledge  of  the  true 
value  of  p  depends  upon  the  determination  of  /',  as  part  of 
the  solvent  leaves  the  solution  as  vapor  under  that  tension; 
therefore  an  error  in  determining  /'  affects  the  result  three 
times  in  the  same  direction.  The  method  is  less  exact  and 
more  inconvenient  than  that  of  determining  the  freezing- 
point. 

A  dynamic  way,  applied  under  Ostwald's  direction  by 
Walker,2  is  very  much  easier:  determine  the  amount  of  water 
which  different  solutions  will  yield  to  the  same  amount  of  air. 
The  measurements  are  made  on  the  balance,  and  the  appa- 
ratus consists  of  one  set  of  bulbs  to  contain  the  solution, 
another  to  hold  an  absorbent  for  water,  and  an  aspirator. 
The  method  has  been  generalized  by  Will  and  Bredig3  for 
other  solvents. 

Lowering  the  tension  means  raising  the  point  of  ebullition 

1  Z.  physik.  Chem.  2,  353  seq.,  405  seq.  (1888). 

2  Z.  physik.  Chem.  2,  602  (1888). 
8  Berichte,  21,  1084  (1889). 


28  MORRIS  LOEB 

for  normal  pressure,  and  the  boiling-point  is,  of  course, 
capable  of  most  exact  determination.  The  method  has  been 
elaborated  by  Beckmann,1  while  the  reader  will  remember 
a  recent  paper  by  Wiley  on  this  subject,  which  does  not,  how- 
ever, give  sufficient  details,  as  Beckmann's  paper  had  al- 
ready been  announced. 

The  latter 's  apparatus  consists  of  a  vessel  of  about  100  cc. 
capacity,  having  a  rounded  bottom  and  three  necks.  Of  these, 
the  central  one  connects  with  a  Soxhlet  condenser,  the  second 
carries  a  Beckmann  thermometer,  whose  bulb  is  completely 
submerged,  and  the  third  neck  serves  for  the  introduction  of 
the  substance. 

Steady  boiling  is  assured  by  filling  the  vessel  to  a  certain 
height  with  beads  or  garnets,  and  by  sealing  platinum  wires 
into  the  bottom  to  promote  conduction.  The  pure  solvent  is 
first  raised  to  the  boiling-point,  its  temperature  noted,  and 
the  weighed  substance  is  thereupon  introduced.  As  soon  as 
the  thermometer  has  become  constant,  the  rise  is  noted;  a 
fresh  quantity  of  substance  may  then  be  introduced,  and 
the  observation  repeated.  The  formula  for  the  molecular 
elevation  of  the  boiling-point  is  precisely  like  that  found  by 
van  't  Hoff  for  the  freezing-point, 

0.02  T2 
t  = > 

W 

with  the  exception  that  here  T  means  the  boiling-point  of  the 
pure  liquid  and  W  its  heat  of  vaporization.  The  constant  t 
being  found  by  calculation  or  experiment,  whenever  we  deter- 
mine that  for  p  grams  of  substance  to  100  grams  of  solvent 
there  is  an  elevation  e,  the  molecular  weight  of  the  sub- 
stance being  M , 

M^ 
e 

1  Z.  physik.  Chem.  t,  532  (1880). 


OSMOTIC  PRESSURE  29 

The  experimental  data  to  show  the  value  of  this  method 
have  not  been  published  as  yet,  but  it  appears  to  be  des- 
tined to  play  as  great  a  part  as  does  the  freezing-point 
method  introduced  in  its  most  convenient  form  by  the  same 
chemist. 


ELECTROLYTIC  DISSOCIATION:  A  REVIEW  OP 
THE  HYPOTHESIS  OP  SVANTE  ARRHENIUS l 

IN  1857,  almost  simultaneously,  Williamson  and  Clausius 
put  forward  the  hypothesis  that,  in  the  fluid  state  at  least,  the 
molecules  of  compounds  are  not  stable,  in  the  sense  that  they 
are  persisting  aggregations  of  the  identical  molecules  which 
originally  united  to  form  them;  on  the  contrary,  it  was  as- 
sumed that  these  molecules  in  so  far  resemble  living  organ- 
isms that,  while  the  external  appearance  remains  unchanged, 
the  constituents  are  constantly  being  cast  off  and  replaced 
by  new  ones  of  the  same  kind,  so  that  there  must  always  be  a 
few  molecules  in  a  state  of  dissociation.  This  hypothesis  has 
been  favorably  regarded  as  an  explanation  of  the  possibility 
of  the  coexistence  of  two  opposing  reactions,  like  those  of 
etherification  and  saponification,  where  it  is  left  to  the  chance 
encounter  of  molecules  to  occasion  the  existence  of  water  and 
ether,  or  of  alcohol  and  acid;  it  has  likewise  been  regarded 
as  a  plausible  explanation  of  the  readiness  with  which  an 
electrolyte  will  obey  the  influence  of  currents  so  feeble  that 
their  energy  should  not  suffice  to  decompose  a  single  mole- 
cule whose  atoms  were  held  together  by  their  full  chemical 
attraction.  But  when,  six  years  ago,  the  attempt  was  made 
by  Arrhenius  to  give  a  quantitative  expression  to  the  hypoth- 
esis and  to  apply  it  to  the  explanation  of  all  the  anomalies  ob- 
served in  the  physical  behavior  of  solutions,  much  latent 
hostility  was  called  forth,  and  a  general  discussion  was  aroused, 
which  has  continued  until  the  present  time.  It  appears,  how- 
ever, to  the  reviewer  that  a  point  has  now  been  reached 
where  the  burden  of  proof  should  rest  upon  the  opponents 

1  Reprinted  from  Am.  Chem.  Journ.  12,  506  (1890). 


ELECTROLYTIC  DISSOCIATION          31 

rather  than  upon  the  supporters  of  the  hypothesis.  An  analy- 
sis of  this  discussion,  set  forth  in  proper  order,  might  prove 
both  lengthy  and  confusing,  and  I  therefore  relegate  a  chrono- 
logical list  of  the  original  papers  to  the  end  of  this  review  and 
confine  myself  to  a  brief  exposition  of  the  hypothesis  as  it 
stands  at  present,  and  of  the  chief  objections  which  have 
been  raised  to  it. 

The  fundamental  idea  is  this:  In  electrical  conductors  of 
the  second  class  electricity  can  be  transported  only  by  elec- 
trically "active"  molecules,  i.e.,  those  in  which  the  electro- 
static charges  are  not  neutralized  within  the  molecule;  the 
ions  are  able  to  receive  and  transport  charges,  positive  and 
negative  respectively,  as  long  as  they  are  separated,  but  not 
when  they  are  firmly  knit  into  a  neutral  molecule.  It  follows 
that  there  can  be  no  conduction  without  a  preexistent  partial 
dissociation  of  the  molecules,  which  may  be  occasioned  either 
by  heat  or  more  generally  by  the  presence  of  a  foreign  body, 
such  as  water.  It  is,  for  instance,  a  well-known  fact  that  some 
of  the  best  conductors,  like  the  strong  acids,  become  insula- 
tors when  freed  from  the  last  traces  of  water,  while  water 
itself  is  classed  among  the  poorest  conductors  when  free  from 
impurities.  The  mechanism  by  which  water,  par  excellence, 
should  produce  electrolytic  dissociation,  while  alcohol  and 
other  solvents  do  not,  has  yet  to  be  explained;  it  does  seem 
strange  that  such  an  effect  should  be  produced  without  a  cor- 
responding dissociation  of  the  water,  an  idea  which  Arrhen- 
ius  rejects  or  admits  only  to  a  minimal  extent.  However 
that  may  be,  electrolytic  dissociation  is  assumed  to  be  a  phe- 
nomenon closely  corresponding  to  gaseous  dissociation  and 
obedient  to  laws  expressed  by  the  same  thermodynamic  for- 
mulae, with  this  difference,  that  "osmotic"  pressure  must 
replace  gas  pressure.  Consequently,  dissociation  must  be 
increased  by  dilution  (increase  of  volume)  and  by  heat;  but 


32  MORRIS  LOEB 

for  different  substances  the  corresponding  coefficients  may 
differ. 

1.  The  first  application  of  this  hypothesis  affects  Kohl- 
rausch's  law  of  conduction;1  the  conducting  power  of  an  elec- 
trolyte is  no  longer  the  sum  of  the  velocities  of  all  the  ions, 
but  of  that  proportion  which  are  free  to  move.    Only  for 
extreme  dilutions  do  we  find  a  rigorous  adherence  to  the 
equation  \=u+v,  which   becomes   in  less  dilute  solutions 
\  =  a(u +v)    (I),  where  a  expresses   the  "coefficient  of   ac- 
tivity," or  that  proportion  of  the  whole  number  of  mole- 
cules which  is  dissociated.    Experiments  having  given  very 
reliable  results  for  u  and  v  in  the  case  of  quite  a  number  of 
ions,  and  X  being  known  for  a  large  number  of  compounds 
at  various  degrees  of  concentration,  the  respective  values  of 
a  are  readily  obtained. 

2.  The  number  of  molecules  in  the  solution  is  increased  by 
the  dissociation.   If  each  molecule  is  dissociated  into  k  con- 
stituent ions,  and  n\  molecules  are  thus  broken  up,  while  n 
remain  associated,  the  osmotic  pressure  must  correspond  to 
the  presence  of  n+krii  molecules,  instead  of  n+ni.  We  shall 
have  for  the  relation  of  the  true  osmotic  pressure  to  that 
calculated  upon  the  assumption  that  the  molecules  remain 

intact,  i 

The  definition  of  the  coefficient  of  activity  has  introduced 
the  value  a= — — >  whence 


-l)a  (II) 

This  explains  the  fact,  alluded  to  in  a  recent  review,  that 
the  molecular  weight  of  an  electrolyte,  as  determined  by  any 
of  the  "osmotic"  methods,  must  be  found  smaller  than 

1  Compare  Am.  Chem.  Journ.  11,  116  (1889). 


ELECTROLYTIC  DISSOCIATION          33 

theory  would  require.  The  coefficient  i  has  been  determined 
for  many  electrolytes,  both  by  the  freezing-point  method  and 
de  Vries's  and  Hamburger's  isotonism  methods,  and  has  in 
almost  every  case  been  found  to  agree  astonishingly  well 
with  the  corresponding  value  obtained  from  equation  II, 
after  calculating  a  by  equation  I.  The  few  exceptions  are 
found  for  salts  which  behave  anomalously  in  other  respects, 
andfcan  be  explained  by  making  further  assumptions  which 
need  not  be  discussed  here. 

3.  If  k  =2,  that  is  if  the  electrolyte  consists  of  but  two 
ions,  as  in  the  case  of  monobasic  acids  and  their  salts  with 
monovalent  metals,  the  dissociation  ought  to  obey  the  law 
which  has  been  found  to  hold  for  gaseous  dissociation  where 

one  molecule  breaks  up  into  two  constituents,  —  =  const., 

Pi 

p  now  referring  to  the  osmotic  pressure  of  the  integral  mole- 
cules and  pi  to  that  of  either  set  of  ions  of  the  dissociated 
ones.  The  osmotic  pressure  depends  upon  the  number  of 
molecules  in  the  unit  volume  of  solution.  Therefore,  if  we 

call  the  volume  of  the  solution  V9  p=—  ,  p\=—  l,  and  —  = 

V         V  n\ 

const. 

If  the  dissociation  were  complete,  a  result  reached  at  in- 
finite dilution,  the  molecular  conductivity  would  reach  a 
maximum  value  /m«>,  but  at  the  finite  dilution  F,  it  has  a 
smaller  value  pv9  which  is  a  measure  of  the  number  of  dis- 
sociated molecules  in  the  total.  We  can  substitute  in  the 

last  equation  the  value  n\=—  »  and  n=l-^-£»  and  obtain 


In  this  form  the  ratio  has  been  examined  by  Ostwald, 
and  has  been  found  to  remain  practically  constant  for  any 


34  MORRIS  LOEB 

one  substance  from  one-fourth  normal  solution  up  to  the 
very  highest  dilution  amenable  to  experiment.  For  different 
acids,  this  constant  assumes  different  values  which  have 
proved  to  be  closely  connected  with  the  chemical  activity  of 

these  acids.  Putting  m=^  and  K=-,  we  can  note  for  refer- 

fr  C 

ence  the  equation  to  which  Ostwald  now  reduces  his  results : 

— ^— =K    (III) 
(l-m)F 

4.  If  the  solution  of  an  electrolyte  really  contains  free 
ions,  how  is  it  that  this  does  not  at  once  become  apparent, 
either  by  the  decomposition  of  water,  or  by  some  physical 
heterogeneity  of  the  system?   The  answer  lies  in  the  further 
definition  that  these  free  ions  bear  equal  and  opposite  electro- 
static charges,  which  do  not  permit  any  local  preponderance 
of  one  sort  of  ions  over  another,  as  this  would  mean  a  local 
accumulation  of  electricity  in  a  system  which  is  in  equi- 
librium.   Consequently  —  although  the  ions  travel  with  dif- 
ferent velocities  —  if  they  are  traveling  in  the  same  direction 
as  in  diffusion,  the  attraction  of  their  electrostatic  charges 
compels  them  to  accommodate  their  rates  one  to  another,  so 
that  the  slower  ion  is  accelerated  while  the  faster  is  retarded; 
the  rate  of  diffusion  of  the  salt  is  therefore  intermediate  be- 
tween the  velocities  of  the  two  ions.  These  conditions  have 
received  a  rigorous  mathematical  formulation,  and  the  close 
agreement  between  the  theoretical  and  experimental  results 
affords  a  beautiful  confirmation  of  the  fundamental  hypoth- 
esis.  (Nernst.) 

5.  Any  cause,  on  the  other  hand,  which  produces  a  rela- 
tive dislocation  of  the  positive  and  negative  ions  must  occa- 
sion electrical  heterogeneity,  showing  itself  by  differences 
of  potential  at  different  points.    Upon  this  idea  a  plausible 


ELECTROLYTIC  DISSOCIATION          35 

"osmotic"  theory  of  voltaic  electricity  has  been  based  and 
substantiated  by  experiment.    (Nernst.) 

6.  Conversely,  any  difference  of  electrical  potential  in  the 
solution  must  produce  a  motion  of  the  ions.   Here  we  have 
the  Clausius  hypothesis  of  electrolysis.   The  introduction  of 
electrodes  disturbs  the  equilibrium  of  the  solution,  the  posi- 
tive ion  moves  to  the  cathode,  where  it  gives  up  its  charge, 
while  the  negative  ion  does  the  same  at  the  cathode.    It  is 
only  when  the  ions  are  relieved  of  their  charges  that  they  are 
capable  of  attacking  the  metal  of  the  electrodes,  or  of  de- 
composing water,  causing  the  well-known  secondary  effects; 
charged,  and  in  the  paralyzing  presence  of  an  opposite  charge, 
they  are  supposed  to  be  incapable  of  doing  this.    In  this 
connection  may  be  cited  an  experiment  which  appears  in- 
comprehensible unless  free  ions  are  assumed  to  exist  in  the 
solution.    Dilute  sulphuric  acid,  contained  in  a  flask  whose 
exterior  was  coated  with  tin  foil,  was  connected  by  a  wick 
with  aLippmann  electrometer;  upon  giving  a  positive  charge 
to  the  exterior  of  the  flask  the  electrometer  indicated  the 
presence  of  positive  electricity,  and  some  bubbles  of  hydro- 
gen were  evolved  near  it.    Consequently,  the  flask,  being  a 
modified  Leyden  jar,  negative  ions  (SO4)  had  collected  on  the 
interior,  while  the  corresponding  hydrogen  had  been  driven 
over  toward  the  electrometer. 

7.  Properties  like  density,  refractive  power,  capillarity 
and  viscosity  of  saline  solutions,  whose  numerical  values  ap- 
pear to  depend  upon  the  sum  of  two  factors  characteristic  of 
the  acid  and  of  the  metal,  should  show  this  additive  nature 
best  where  the  salts  are  most  dissociated;  this  appears  to  be 
the  case. 

8.  We  have  now  to  consider  the  chemical  side  of  the 
hypothesis,  and  we  are  met  by  the  startling  assertion  that 
those  acids  show  the  greatest  degree  of  dissociation  which  we 


36  MORRIS  LOEB 

consider  the  strongest.  Indeed,  according  to  Arrhenius, 
chemical  activity  depends  upon  the  degree  of  electrolytic  dis- 
sociation, only  the  dissociated  molecules  being  capable  of 
entering  into  reaction.  A  fundamental  difference  is  hereby 
inferred  to  exist  between  reactions  among  electrolytes  and 
reactions  introducing  only  non-electrolytes,  or,  to  recall 
antiquated  notions,  between  reactions  which  involve  sub- 
stances of  the  water  and  hydrochloric  acid  types,  and  those 
involving  merely  the  hydrogen  and  ammonia  types.  Valid 
objections  raised  to  this  distinction  would  upset  the  theory 
from  the  chemist's  standpoint:  examples  in  favor  of  the  dis- 
tinction have  been  adduced,  such  as  the  fact  that  the  char- 
acteristic halogen  reaction  with  silver  nitrate  is  only  shown 
by  such  compounds  in  which  the  halogen  can  be  supposed  to 
exist  as  a  free  ion,  while  with  those  which  contain  the  halo- 
gen within  the  radicle,  like  trichloracetic  acid,  the  reaction 
fails.  Considering  by  themselves  the  reactions  between 
electrolytes,  it  is  noticeable  that  the  presence  of  water  or 
another  solvent  appears  to  be  necessary  (cf .  the  passivity  of 
absolutely  dry  gases).  The  law  of  Guldberg  and  Waage  must 
be  modified  in  so  far  that  the  speed  of  reaction  is  not  a  func- 
tion of  the  total  masses  of  the  electrolytes  in  solution,  but 
of  the  masses  of  dissociated  ions :  van  't  Hoff  has  introduced 
the  coefficient  i  (isotonic  coefficient)  successfully  enough  into 
these  considerations,  and  i  has  already  been  shown  to  be  a 
function  of  a  (II).  In  the  acceleration  or  retardation  of 
etherification  and  saponification,  the  acids  and  bases  must 
act  proportionately  to  their  stages  of  dissociation,  so  that 
Ostwald's  old  affinity-coefficients  must  correspond  with  the 
values  of  k  in  equation  III,  which  is  also  found  to  be  true; 
for  the  same  reason  the  effectiveness  of  weaker  acids  (non- 
dissociated)  increases  more  rapidly  for  additional  dilution 
than  does  that  of  stronger  acids  which  are  much  nearer  their 


ELECTROLYTIC  DISSOCIATION          37 

limit.  The  evidence  to  be  obtained  from  the  study  of  the 
kinetics  of  chemical  reaction  all  appears  to  favor  the  theory. 
9.  New  ideas  are  introduced  with  regard  to  chemical  equi- 
librium. The  laws  of  dissociation,  where  gases  are  concerned, 
lead  to  the  well-established  postulate  that  dissociation  shall 
be  greatest  where  the  atmosphere  contains  no  excess  of  either 
of  the  constituents  into  which  the  molecule  will  break  up;  dis- 
sociation is  unaffected  by  the  presence  of  any  other  indiffer- 
ent substances.  By  analogy,  if  a  solution  already  contains  a 
number  of  free  ions  of  a  particular  sort,  any  substance  con- 
sisting in  part  of  this  same  sort  of  ions  will  not  dissociate  as 
fully  as  in  pure  water.  Consequently  an  acid  will  be  weak- 
ened by  the  presence  of  one  of  its  neutral  salts,  but  the  effect 
will  be  much  more  perceptible  for  a  weak  acid  than  for  a 
strong  one.  This  has  been  verified  by  Arrhenius.  Comparing 
on  the  other  hand,  acids  which  have  the  positive  ion  H  in 
common,  a  mixture  of  the  two  must  affect  their  respective 
degrees  of  dissociation,  unless  before  mixing  the  H  had  the 
same  osmotic  partial  pressure  in  both  solutions.  This  means 
that  there  shall  be  the  same  degree  of  dissociation  in  the 
two  solutions,  that  they  shall  be  "isohydric."  Under  such 
conditions,  if  ra  parts  of  one  solution  having  the  conductivity 
a  be  mixed  with  n  parts  of  the  other  having  the  conductivity 
6,  the  resulting  solution  will  conduct  as  if  each  electrolyte 
were  conducting  independently  and  unchanged.  Its  conductiv- 
ity is  -  — ,  no  matter  what  the  relative  values  of  m  and 
m+n 

n  are.  Furthermore,  if  two  solutions  are  "isohydric"  with  a 
third,  they  must  be  isohydrous  with  each  other.  These  two 
consequences  have  been  substantiated  by  the  examination 
of  the  conductivity  of  mixtures  of  "isohydric"  solutions  of 
acids  with  one  another  and  with  those  of  their  respective 
neutral  salts,  of  neutral  salts  with  one  another  and  with  the 


38  MORRIS  LOEB 

solutions  of  their  respective  bases,  and  finally  of  the  bases 
with  one  another. 

But  if  solutions  are  mixed  together  which  are  not  "iso- 
hydric,"  the  resultant  conductivity  will  be  greater  than 

ma        ,  if  calculation  shows  that  the  stronger  acid  is  thereby 
m+n 

partially  reassociated  and  the  weaker  partially  dissociated, 
while  it  will  be  less  than  the  normal  if  the  stronger  acid  is 
being  dissociated  and  the  weaker  reassociated.  This  depends 
upon  the  fact  that  the  dissociation  of  the  same  number  of 
molecules  produces  a  relatively  greater  effect  when  the  acid 
is  farther  from  the  limit  of  dissociation  which  all  approach 
asymptotically.  In  keeping  with  these  facts  is  Nernst's  ob- 
servation that  the  solubility  of  a  salt  is  decreased  by  the  pres- 
ence of  compounds  having  a  common  ion  with  it;  thus  the 
solubility  of  silver  acetate  is  equally  affected  by  the  pres- 
ence of  silver  nitrate  and  sodium  acetate. 

10.  The  theory  of  "isohydric"  solutions  leads  up  to  the 
important  point  of  the  neutralization  of  acids  by  bases.  In 
the  first  place,  salts  in  dilute  solutions  are  no  longer  con- 
sidered to  be  the  product  of  a  reaction  like  the  following :  — 

KOH+HC1 =KC1+HOH. 

Where  there  is  perfect  dissociation,  at  extreme  dilutions, 
the  reaction  is  represented  thus :  — 

K+OH+Cl+H=K-fCl+HOH. 

At  greater  concentrations  this  is  accompanied  by  a  certain 
reassociation  of  K-j-Cl  and  a  dissociation  K,  OH  and  H,  Cl, 
but  K+C1  is  supposed  to  be  very  small  in  all  cases,  as  the 
dissociation  of  salts  proves  to  be  relatively  very  great.  Neu- 
tralization would  therefore  practically  mean  a  formation  of 
water  from  H  and  OH,  and  salts  as  such  would  only  exist  in 
concentrated  solutions  or  as  a  combination  of  a  very  weak 
acid  with  a  very  weak  base.  A  result  of  this  would  be  that 


ELECTROLYTIC  DISSOCIATION          39 

the  heat  of  neutralization  in  dilute  solutions  should  be  the 
same  for  all  sorts  of  strong  acids  and  bases,  and  should,  in 
fact,  equal  that  produced  by  the  reaction  H+OH,  a  very 
familiar  fact.  Mixtures  of  such  salts  should  not  be  accom- 
panied by  a  heat  effect,  which  explains  the  phenomenon  of 
thermo-neutrality.  But  a  weak  base  or  a  weak  acid  introduces 
the  positive  or  negative  heat  of  dissociation  pertaining  to  it; 
consequently  the  thermal  effect  of  neutralization  must  vary 
from  that  of  H+OH,  but  this  variation  must  decrease  with 
the  increase  of  temperature.  If  a  stronger  and  a  weaker  acid 
are  together  mixed  with  a  base,  it  is  only  the  weaker  anion  which 
really  unites  with  the  metal  to  a  limited  extent,  while  the 
stronger  anion  keeps  the  relatively  greater  amount  of  metal 
in  electrolytic  dissociation,  their  neutralization  being  charac- 
terized by  the  union  of  their  former  conjugates  H+OH.  It  is 
noticeable  that  electrolytic  dissociation  is  to  be  sharply 
separated  from  the  hydrolysis  of  sugars  and  of  very  weak 
salts  like  ammonium  acetate,  in  which  the  reaction  belongs 
rather  to  the  class  of  non-electrolytes,  although  electro- 
lytes are  involved. 

A  final  point  with  regard  to  chemical  equilibrium  is  this, 
that  when  equilibrium  has  been  reached  in  a  solution  con- 
taining a  number  of  electrolytes,  each  one  of  these  is  in  a 
state  of  dissociation,  which  depends  upon  the  equilibrium 
of  osmotic  pressure  between  the  non-dissociated  molecules 
and  all  the  free  ions  of  the  kinds  which  compose  it.  A  dis- 
tribution of  metals  and  acids  as  it  is  usually  assumed  in  older 
views  is  therefore  rendered  out  of  question,  because  a  free 
ion  belongs  neither  to  one  compound  nor  to  another,  it 
merely  counterbalances  that  free  ion  of  opposite  charge  near- 
est which  it  happens  for  the  moment  to  be. 

Having  sketched  Arrhenius'  hypothesis,  with  some  of  its 
logical  consequences,  the  task  of  judging  it  must  be  left  to 


40  MORRIS  LOEB 

those  readers  who  will  compare  the  mass  of  experimental 
material  and  will  convince  themselves  of  the  simple  relations 
which  the  various  phenomena  appear  to  bear  toward  each 
other.  As  far  as  this  test  is  concerned,  the  hypothesis  will  be 
found  to  fulfill  its  purpose.  Shall  it  therefore  be  accepted? 

The  objections  which  have  been  raised  are  twofold,  phys- 
ical and  chemical.  Oliver  J.  Lodge  concedes  the  inge- 
nuity and  physical  "orthodoxy"  of  the  treatment,  and  it 
might  appear  that  his  criticisms  to  the  earlier  papers  have 
been  largely  obviated  by  the  further  development  of  the 
theory;  indeed  they  apply  chiefly  to  points  which  I  have 
omitted  as  no  longer  seeming  essential  to  the  theory,  such  as 
relations  between  the  viscosity  and  the  friction  which  a 
solvent  opposes  to  the  motion  of  the  ions.  But  he  appears 
mainly  to  object  to  the  neglect  of  conduction  by  the  solvent, 
which  he  believes  would  explain  the  rate  of  transference 
of  the  ions,  without  the  assumption  of  unequal  velocities  of 
negative  and  positive  ions.  It  is  doubtful  whether  such  an 
explanation  would  also  elucidate  the  troublesome  diffu- 
sion phenomena  as  well  as  does  "dissociation"  in  the  hands 
of  Nernst.  E.  Wiedemann  thinks  that  hydrates  are  the  cause 
of  better  conduction,  and  explains  osmotic  anomalies  by  the 
assumption  of  a  polymerization  of  the  solvent.  Aside  from 
Planck's  proof,  on  thermodynamic  grounds,  that  such  poly- 
merization would  not  affect  the  vapor  tension  phenomenon 
in  this  way,  in  very  dilute  solutions,  Ostwald  pertinently 
asks  why  the  electrolyte  need  cause  a  polymerization  which 
no  non-electrolyte  does. 

The  objections  from  a  chemical  standpoint  have  been 
chiefly  raised  by  Henry  E.  Armstrong,  and  are  not  all  co- 
gent. The  following  appear  to  be  the  most  important  at 
the  present  time:  — 

1.  Anhydrous  hydrochloric  acid  and  pure  water  do  not 


ELECTROLYTIC  DISSOCIATION         41 

conduct,  while  fused  silver  iodide  does,  which  is  an  anomaly. 
Arrhenius  finds  an  explanation  in  the  dissociation  of  silver 
iodide  by  heat. 

2.  Hydrochloric,  hydrobromic  and  hydriodic  acids  differ 
markedly  in  stability,  but  they  are  all  assigned  the  same 
dissociation  ratio.    This  is  evidently  a  case  of  misapprehen- 
sion, as  the  instability  lies  in  the  negative  ion  itself,  and  not 
in  the  compound. 

3.  Why  does  not  alcohol  dissociate  electrolytes  as  well  as 
water,  and  why  does  not  water  conduct? 

4.  According  to  Ostwald's  measurements,  phenylpropionic, 
cinnamic,  and  phenylpropiolic  acids  range  in  the  order  of 
their  conducting  power,  — 

C6H5.C.C.COOH>CftH5.CH.CH.COOH>CflH5.CH2.CH2.COOH. 
Therefore  that  acid  is  most  dissociated  which  can  least  spare 
its  hydrogen. 

This  argument  illustrates  the  necessity  of  keeping  the 
types  of  reactions  apart.  Nothing  appears  to  justify  his  as- 
sumption that  the  carboxyl  group  should  be  affected  in  this 
way  by  what  happens  in  a  neighboring  group,  where  hydro- 
gen plays  an  entirely  different  role. 

The  main  opposition  to  the  dissociation  hypothesis  is  to 
be  found  in  a  rival  hypothesis  which  has  found  advocates 
in  Mendeleeff,  Armstrong,  Pickering,  Crompton,  Bonty  and 
E.  Wiedemann, — the"hydration"  hypothesis  connected  with 
the  "residual  affinity"  idea.  Bonty  holds  that  electrolytes  are 
of  two  classes,  those  in  which  both  ions  show  equal  rates  of 
transference,  and  the  "abnormal"  ones,  in  which  this  is  not 
the  case.  All  abnormal  salts  are  said  to  be  capable  of  form- 
ing hydrates  and  do  so.  The  law  of  equivalent  ratio  holds 
absolutely  in  so  few  cases  that  these  considerations  may 
be  dismissed,  in  view  of  the  more  powerful  ideas  of  Kohl- 
rausch.  E.  Wiedemann  argues  from  the  change  of  color  of 


42  MORRIS  LOEB 

salts  of  nickel,  copper,  cobalt,  etc.,  upon  dilution  and  heating, 
effects  which  Arrhenius  ascribes  to  a  difference  in  color  be- 
tween the  free  ion  and  the  compound.  Armstrong  and 
Pickering  present  the  "residual  affinity"  theory  with  much 
vigor.  The  atomic  valences  are  not  assumed  to  be  whole 
numbers,  so  that  it  rarely  happens  that  the  positive  and 
negative  valences  in  a  compound  just  balance.  Consequently, 
a  small  residual  affinity  remains  to  each  molecule,  by  virtue 
of  which  larger  aggregations  are  formed,  molecular  com- 
pounds, either  among  the  molecules  of  the  same  sort  or  with 
the  molecules  of  the  solvent.  Armstrong's  valences  represent 
the  old  Berzelian  negative  and  positive  electricities,  which 
cause  their  respective  atoms  to  tend  to  opposite  electrodes 
during  the  passage  of  the  current,  the  atoms  being  set  free 
by  the  complexes  "straining"  at  each  other  as  they  pass 
each  other.  The  idea  of  unequal  electrical  charges  appears 
incompatible  with  Faraday's  law  that  the  current  produces 
the  same  effect  in  all  electrolytes.  Pickering  bases  his  opposi- 
tion upon  more  modern  ideas,  separating  affinity  from  elec- 
tric charges,  and  sees  in  the  phenomena  of  electrolysis  and 
dilution  effects  of  the  dissociation  and  formation  of  various 
hydrates.  The  basis  for  this  lies  in  the  observations  by  Men- 
deleeff,  Pickering,  and  Crompton,  that  various  properties  of 
acids  and  salts,  such  as  conductivity,  density,  the  heat  of 
solution,  when  plotted  as  ordinates,  with  the  percentage 
composition  of  the  solution  as  abscissas,  do  not  present  reg- 
ular curves.  A  study  of  their  first  or  second  differentials 
would  appear  to  reveal  the  presence  of  points  of  abrupt 
change,  and  these  points  are  supposed  to  represent  definite 
chemical  compounds.  It  does  not  appear  that  Arrhenius  has 
entirely  invalidated  the  proofs  of  the  existence  of  such  com- 
pounds, and  there  is  no  doubt  that  they  present  a  very 
awkward  obstacle  to  his  theory,  which  he  has  still  to  sur- 


ELECTROLYTIC  DISSOCIATION         43 

mount.  On  the  other  hand,  Pickering's  explanations  of  the 
phenomena  of  freezing  are  extremely  complex,  and  I  am  not 
aware  of  any  positive  attempt  to  explain  facts  like  diffusion 
upon  them.  The  thermo-chemical  phenomena  might  be 
fairly  explained  by  Pickering's  reasoning. 

LITERATURE 

1883.  S.  Arrhenius,  Sur  la  conductibilite    galvanique   des  Electrolytes. 
Bihang  til  Kong.  Vet.  Ak.  Vorh.  1884,  Stockholm. 

1884.  Theorie  chimique  des  Electrolytes. 

Van't  Hoff,  Etudes  de  dynamique  chimique.  Amsterdam. 

1884.  Bonty,  Sur  la  conductibilite,  etc.,  Journ.  de  Physique  (2)  3,  325, 
333. 

1885.  Report  of  the  British  Association  Committee  on  Electrolysis, 
British  Association  Report,  pp.  723-772. 

Pickering,  Proc.  Chem.  Soc.  1,  p.  122. 

1886.  H.  E.  Armstrong,  President's  Address,  Section  C  of  British 
Association  of  1885,  in  Proc.  Royal  Soc.  40,  268. 

Report  of  Electrolysis  Committee  for  1886,  British  Association  Re- 
port, pp.  308-389,  containing  criticisms  and  replies  by  Lodge,  Kohlrausch, 
Arrhenius,  Bonty,  as  well  as  abstracts  of  papers  appearing  elsewhere. 

1887.  Sv.  Arrhenius,  Einfluss  der  Neutralsalze  auf  Verseifungsgeschwind- 
igkeit,  Zeit.  physik.  Chem.  1,  110.   Innere  Reibung  verdiinnter  wdssriger 
Losungen,  ibid.    285.    Theorie  der  isohydrischen  Losungen,  Wied.  Ann. 
Phys.  Chem.  30,  54. 

S.  IT.  Pickering,  The  Influence  of  Temperature  on  the  Heat  of  Dissolution 
of  Salts,  Journ.  Chem.  Soc.  51,  p.  290. 

Mendeleeff ,  Specifisches  Gewicht  der  Schwefelsdurelosungen,  Zeit.-physik. 
Chem.  1,  273. 

Bonty,  Sur  la  conductibilite,  etc.,  Journ.  de  Physique  (2)  6,  p.  6. 

Van  't  Hoff,  Ueber  osmotischen  Druck,  Zeit.  physik.  Chem.  1,  500. 

1888.  British  Association  Report  of  Electrolysis  Committee,  by  O.  J. 
Lodge,  p.  351.   Answers,  by  H.  E.  Armstrong  and  S.  Arrhenius. 

Ostwald,  Zur  Theorie  der  Elektrolyte,  Zeit.  physik.  Chem.  2,  36,  270. 

Planck,  Ueber  Gleichgevrichtszustande,  etc.,  Wied.  Ann.  Phys.  Chem.  34, 
149. 

E.  Wiedemann,  Ueber  die  Hypothese  der  Dissociation,  etc.,  Zeit.  physik. 
Chem.  2,  241. 

Ostwald,  Reply,  ibid.  243. 

Planck,  Reply  to  Wiedemann,  ibid.  343. 

Arrhenius,  Theorie  der  isohydrischen  Losungen,  ibid.  284.  Gefrierpunkte 
verdiinnter  wdssriger  Losungen,  ibid.  491. 

de  Vries,  Osmotische  Versuche,  ibid.  415. 

Nernst,  Zur  Kinetik  der  Losungen,  ibid.  613. 


44  MORRIS  LOEB 

Van  H  Hoff  and  Reicher,  Ueber  die  Dissociationstheorie,  etc.,  ibid.  781. 
Pickering,  Thermochemical  Investigations,  etc.,  Journ.  Chem.  Soc.  63, 865. 

1889.  Pickering,  Nature  of  Solutions,   etc.,  Proc.  Chem.  Soc.  57,   92 
(1888-89);  Journ.  Chem.  Soc.  Trans.  56,  323. 

Ostwald  and  Nernst,  Ueber  freie  lonen,  Zeit.  physik.  Chem.  3,  120. 
Ostwald,  Affinitdtsgrossen  organischer  Sduren,  ibid.  241,  369,  588. 
de  Vries,  Isotonische  Coeffizienten,  ibid.  103. 

Arrhenius,  On  Electrolyte  Dissociation  vs.  Hydration,  Phil.  Mag.  28,  30. 
Arrhenius,  Ueber  die  Dissociationswarme,  etc.,  Zeit.  physik.  Chem.  4,  96. 
Nernst,  Elektromotorische  Wirksamkeit  der  lonen,  ibid.  129. 
Arrhenius,  Reaktionsgeschioindigkeit  bei  Inversion  des  Rohrzuckers,  etc., 
ibid.  226. 

Nernst,  Gegenseitige  Beeinflussung  der  Loslichkeit  von  Salzent  ibid.  372. 
Arrhenius,  Gleichgemchtsverhdltnisse  zwischen  Elektrolyten,  ibid.  6,  1. 

1890.  Pickering,  Nature  of  Solutions,  Proc.  Chem.  Soc.  6,  86  and  Phil. 
Mag.  29,  429. 


A  BRIEF  REVIEW  OF  WILHELM  OSTWALD'S 
"GRUNDRISS  DER  ALLGEMEINEN  CHEMIE  "  1 

A  SINCERE  admirer  of  Professor  Ostwald's  monumental 
"Lehrbuch"  must  regret  that  the  present  textbook  should 
have  been  chosen  to  present  the  recent  developments  of 
physical  chemistry,  rather  than  a  second  edition  of  the 
earlier,  larger  work.  While  the  present  volume  is  intended, 
according  to  the  preface,  to  interest  in  physical  chemistry 
those  as  yet  unacquainted  with  the  subject,  it  seems  question- 
able whether  this  object  can  best  be  obtained  by  cutting  away 
much  that  renders  the  larger  work  such  delightful  reading; 
nor  does  it  seem  plausible  that  a  non-mathematical  mind 
should  grasp  a  mathematical  formula  better  because  the  strict 
proof  is  omitted  as  too  abstruse,  and  that  the  reader  who  is 
conversant  with  calculus  should  therefore  be  debarred  from 
this  aid  to  the  comprehension.  There  is  no  doubt,  however, 
that  this  little  volume  gives  all  the  subject-matter  proper  of 
the  two  older  volumes,  with  some  additions;  condensation 
has  been  obtained  by  employing  smaller  type,  omitting  many 
tables  and  much  purely  historical  matter,  and,  finally,  by 
omitting  all  references  to  titles  of  papers,  instead  of  which 
the  year  of  publication  has  been  inserted  in  the  text.  The  chap- 
ters have  been  rearranged  into  a  very  logical  sequence,  and 
the  new  points  of  view  introduced  by  the  hypothesis  of  os- 
motic pressure  receive  a  very  full  and  withal  very  compre- 
hensible treatment. 

For  such  as  desire  a  rather  hurried  glance  over  a  large 
field,  this  book  can  be  very  well  recommended;  but  it  is  to 
be  hoped  that  its  presence  in  the  chemist's  library  will  not  be 
supposed  to  atone  for  the  absence  of  the  "Lehrbuch." 

1  Reprinted  from  Am.  Chem.  Journ.  12,  516  (1890). 


THE  PROVINCE  OF  A  GREAT  ENDOWMENT  FOR 

RESEARCH l 

IN  response  to  the  request  for  the  views  of  American  men 
of  science  on  the  mission  of  the  Carnegie  Institution,  I  would 
first  of  all  express  the  hope  that  the  trustees  will  reject  those 
propositions  which  would  most  seriously  menace  the  free  de- 
velopment and  untrammeled  activity  of  our  various  scientific 
bodies  and  institutions  of  learning  —  especially  the  establish- 
ment of  a  huge  reserve  fund,  with  the  annual  distribution  of 
its  income  among  the  "  deserving  poor."  It  seems  to  me  that, 
while  there  may  be  occasional  demands  for  large  sums  to  equip 
exploring  parties  on  behalf  of  some  of  the  descriptive  sciences, 
the  legitimate  demands  for  assistance  in  research  in  the  exact 
sciences  ought  not  to  be  very  large,  in  any  one  year;  in  fact, 
I  venture  the  assertion  that  the  existence  of  large  sums  to  be 
devoted  in  this  way  might  lead  to  wastefulness  in  methods, 
rather  than  to  the  development  of  that  resourcefulness  which 
has  been  the  characteristic  of  the  greatest  investigators. 
Favored  beneficiaries  might  choose  a  field  of  work  from  which 
others  would  be  debarred  by  questions  of  cost,  rather  than 
strike  out  upon  lines  of  greater  originality  and  importance. 
Again,  it  cannot  be  denied  that  the  establishment  of  a  stand- 
ard of  measurement  with  the  utmost  precision  is  work  well 
worthy  of  national  support:  but  if  the  Carnegie  Institution 
were  to  encourage,  by  means  of  its  stipends,  all  our  most  capa- 
ble physicists  to  devote  themselves  to  this  class  of  work,  ad- 
vance in  this  department  of  knowledge  would  be  seriously 
hampered.  Is  it  a  hardy  prediction,  however,  that  the  votes  of 

1  Reprinted  from  Science,  N.  S.,  vol.  16,  1902,  pp.  485-86. 


ENDOWMENT  FOR  RESEARCH          47 

a  committee  on  distribution  would  always  favor  such  definite 
projects,  as  against  a  proposition  to  explore  some  vaguely  de- 
fined problem  of  physics  or  chemistry? 

I  think,  therefore,  that  the  proportion  of  the  income  to  be 
devoted  to  the  immediate  subvention  of  research  ought  to  be 
small  at  best;  the  aid  would  probably  be  more  efficient,  if 
administered  through  existing  scientific  societies,  who  would 
receive  from  time  to  time  such  additions  to  their  research 
funds  as  would  seem  commensurate  with  their  previous  suc- 
cess in  promoting  investigation.  The  existence  of  a  central 
reviewing  body  would  act  as  a  wholesome  restraint  upon  these 
smaller  scientific  bodies,  while  the  relative  needs  of  investi- 
gators could  be  better  judged  by  a  jury  of  experts  in  their  im- 
mediate field  of  work,  than  by  such  a  heterogeneous  committee 
as  would  be  furnished  by  the  trustees  themselves. 

On  the  other  hand,  the  suggestion  that  the  institution 
should  play  the  part  of  a  private  benefactor  to  our  universi- 
ties, by  adding  to  their  endowment,  building  and  equipping 
laboratories,  augmenting  professors'  salaries  or  providing 
them  with  private  assistants,  seems  to  me  to  savor  of  paternal- 
ism and  to  open  the  way  to  serious  abuses,  while  at  the  same 
time  it  might  cause  colleges  to  shape  their  course  with  the  sole 
view  of  pleasing  the  guardians  of  the  fund,  for  the  time  being. 

It  seems  doubtful  whether  any  salary  could  be  paid  to  a 
body  of  academicians,  sufficient  to  enable  them  to  devote 
their  whole  time  to  research;  and  it  is  a  fair  question  whether 
it  would  really  be  desirable  to  set  a  body  of  men  apart  in  a 
scientific  academy,  at  the  present  day,  without  that  contact 
with  students  which  a  university  provides.  It  must  be  remem- 
bered that  the  Royal  Institution  of  London  is  not  an  academy 
in  the  strictest  sense;  nor  do  the  resident  lecturers  owe  a  duty 
to  a  foundation,  but  rather  to  the  subscribers.  With  the 
enormous  distances  separating  our  educational  centres,  it 


48  MORRIS  LOEB 

would  not  be  conceivable  that  a  lecturer  could  assemble 
around  him  so  national  an  audience  as  would  listen  to  a  Fara- 
day or  a  Rayleigh. 

All  these  plans  remind  one  of  the  hot-house  method  of  stim- 
ulating plant-growth;  why  not  attempt  the  open-air  method 
of  cultivating  the  soil?  The  Carnegie  Institution  might  facili- 
tate research  for  all,  instead  of  offering  incentives  to  a  chosen 
few.  For  this  reason,  the  satisfactory  equipment  of  marine 
biological  stations,  open  to  all  qualified  observers,  and  of 
similar  institutions  that  would  render  the  natural  phenomena 
more  readily  accessible  to  general  study,  would  seem  eminently 
proper;  while  one  might  doubt  the  propriety  of  establishing 
observatories  simply  for  the  intense  study  of  single  problems. 
The  efficacy  of  special  research  laboratories  in  the  physical 
sciences,  such  as  England  owes  to  the  generosity  of  Mr.  Mond, 
has  yet  to  be  proven  in  contrast  with  that  of  university  labora- 
tories; to  the  writer,  their  establishment  in  this  country  would 
appear  premature,  since  many  of  our  well-equipped  educa- 
tional laboratories  are  not  so  crowded  that  they  would  be 
obliged  to  refuse  accommodation  to  an  independent  investi- 
gator who  sought  their  hospitality. 

The  same  general  argument  would  oppose  the  financial 
support  of  periodicals  and  publishing  organizations,  while  it 
would  strongly  favor  the  equipment  of  a  scientific  printing 
office,  for  the  prompt  and  cheap  reproduction  of  the  results  of 
research,  for  the  account  of  individuals  as  well  as  of  associa- 
tions. However,  if  the  trustees  desired  to  obviate  the  most 
serious  difficulties  which  beset  the  American  scientist  in  his 
laboratory  work,  they  would  establish  workshops  for  the  con- 
struction of  special  apparatus  and  the  preparation  of  the 
more  recondite  materials,  such  as  rare  chemicals,  microscopic 
mounts,  etc.  What  stipend,  for  instance,  could  put  the  Ameri- 
can chemist  on  a  level  with  his  German  colleague,  when  the 


ENDOWMENT  FOR  RESEARCH          49 

latter  can  obtain,  within  twenty-four  hours,  any  preparation 
that  is  catalogued,  while  the  former  must  allow  six  weeks  for 
obtaining  anything  that  is  not  so  commonly  known  as  to  be 
literally  a  "drug  on  the  market"?  By  enabling  the  private 
investigator  to  supply  his  needs  quickly  and  at  a  reasonable 
cost,  without  the  unjust  discrimination  of  "  duty-free"  impor- 
tation, a  stimulus  would  be  given  to  private  research,  inside 
and  outside  the  college  laboratory.  Who  can  estimate  the 
amount  of  time  frittered  away  in  this  country  through  the 
lack  of  ready  access  to  the  mechanical  adjuncts  to  investiga- 
tion? Workshops  to  supply  these  would  not  only  improve  our 
immediate  condition;  but,  if  properly  organized,  they  might 
serve  to  educate  a  body  of  mechanicians  and  preparators, 
whose  help  would  be  invaluable  in  the  various  scientific  in- 
stitutions of  the  country. 

If  these  suggestions  should  illustrate  the  view  that  the 
Carnegie  Institution  can  do  measurable  harm  by  seeking  to 
supplant  private  initiative  with  artificial  stimulus,  but  can  do 
immeasurable  good  by  clearing  away  the  obstacles  that  now 
trammel  the  general  growth  of  the  scientific  spirit  in  America, 
they  will  best  express  the  opinion  of 

MORRIS  LOEB. 


ATOMS  AND  MOLECULES1 

IT  is  often  a  question  with  the  scientific  student  as  to 
whether  his  investigation  can  lead  to  any  real  advancement  of 
knowledge,  or  whether  the  outcome  will  merely  add  to  the 
scraps  of  information  that  are  scattered  here  and  there  in  the 
storehouse  of  human  intelligence.  How  often,  when  walking 
or  bicycling  in  an  unfamiliar  country,  does  one  turn  into  a 
lane,  wondering  whether  it  is  to  lead  one  into  a  new  highway 
or  end  blindly ,  forcing  the  traveler  to  retrace  his  path !  Fortu- 
nately, the  many  discoveries  and  inventions  based  on  studies 
by  previous  generations  made  without  any  expectation  of  a 
practical  outcome,  have  silenced  those  who  scoff  at  anybody 
who  looks  for  something  that  cannot  at  once  be  made  into  a 
scarf-pin  or  shoe-buttoner  or  patent  medicine  or  the  like. 

Among  the  matters  that  will  necessarily  escape  practical 
application  longest  are  the  infinitely  great  and  the  infini- 
tesimally  small.  It  is  true  enough  that  astronomy  is  a  useful 
science  to  the  navigator  and  to  the  geographical  surveyor; 
but  it  would  be  hard  to  convince  me  that,  for  many  genera- 
tions to  come,  the  price  of  iron  will  be  affected  by  our  knowl- 
edge that  huge  quantities  of  that  metal  exist  in  the  solar 
atmosphere.  Nevertheless,  it  gives  us  a  wonderfully  encourag- 
ing realization  of  the  power  of  the  human  intellect  to  con- 
template the  steps  by  means  of  which  this  apparently  useless 
bit  of  knowledge  was  secured.  How  grand  is  the  thought  that 
a  Lilliputian  man  has  been  able  to  weigh  heavenly  bodies 
far  bigger  than  the  earth  itself,  and  so  far  distant  that  our  own 
distance  from  the  sun  becomes  quite  small  by  comparison! 

1  A  popular  address  evidently  delivered  in  the  spring  of  1906;  the  place  and  exact 
time  are  unknown.  This  address  was  illustrated  by  experiments.  [EDITOR.] 


ATOMS  AND  MOLECULES  51 

Chemistry  and  physics,  however,  bring  us  to  the  opposite 
end  of  the  scale,  and  we  are  led  to  the  assumption  of  bodies 
that  are  so  exceedingly  small  and  so  close  together,  that  we 
cannot  conceive  of  their  dimensions  any  more  clearly  than 
we  can  conceive  of  our  distance  from  the  sun  or  from  Neptune. 
The  problem  of  estimating  these  distances  must,  therefore, 
appeal  to  us  as  similarly  deprived  of  immediate  usefulness. 

There  is  nevertheless  this  difference.  We  are  all  convinced 
of  the  existence  of  the  stars :  we  follow  HerschePs  descrip- 
tion of  their  multitude  with  amazement,  but  we  do  not  for 
a  moment  doubt  the  reality  of  his  statements.  The  atom 
and  the  molecule  are  every  now  and  then  denied  reality;  that 
great  thinker,  Ostwald,  who  visited  us  this  winter,  has  emphat- 
ically expressed  the  opinion  that  matter  itself  is  non-existent 
and  that  the  atom  and  molecule  are  conceptions  which  must 
sooner  or  later  be  abandoned.  The  permanence  of  the  atom 
is  assailed  by  the  supporters  of  the  new  electron  theory  and  is, 
in  a  measure,  shaken  by  recent  discoveries  respecting  radium 
and  helium.  How  about  the  molecule?  It  is  too  small  to  be 
seen,  too  subtle  to  be  handled  and  weighed  as  an  individual. 
But  we  can  nevertheless  weigh  and  measure  it  by  different 
means;  and  because  results  attained  in  various  ways  agree 
fairly  well  with  one  another,  strong  evidence  is  afforded  of  the 
reality  of  the  molecule.  It  would  be  a  very  remarkable  coinci- 
dence if  three  or  four  different  processes  gave  us  an  identical 
measure  for  a  certain  thing  and  the  thing  itself  did  not  exist. 
If,  in  traveling,  we  noticed  a  considerable  number  of  rail- 
roads converging  toward  a  common  centre,  we  should  expect 
to  find  something  interesting  and  definite  at  that  point. 
Similarly,  I  see  evidence  of  the  probable  existence  of  the 
molecule  in  the  fact  that  many  lines  of  calculation  converge 
upon  the  same  order  of  magnitude. 

The  ancient  philosophers  who  first  thought  concerning  the 


52  MORRIS  LOEB 

nature  of  substances  as  we  see  them  around  us,  had  many 
vague  notions  as  to  the  causes  from  which  the  various  proper- 
ties of  the  substances  might  arise.  One  might  almost  say  that 
the  various  Greek  philosophers  devised  every  conceivable 
notion  as  to  the  origin  of  matter  which  a  sensible  man  could 
happen  upon.  Among  these  there  were  two  which  must  claim 
our  attention,  because  they  throw  much  light  upon  the  differ- 
ing hypotheses  about  physical  phenomena  up  to  the  present 
day.  One  notion  was  that  every  substance  is  made  up  of  cer- 
tain ingredients  whose  presence  caused  it  to  have  its  own  par- 
ticular properties,  which  were  really  the  properties  of  the  in- 
gredients. Aristotle  called  these  ingredients  elements,  and 
he  mentioned  as  such  elements,  fire,  air,  earth  and  water,  of 
which  he  considered  earth  as  that  which  was  cold  and  dry, 
water  that  which  was  cold  and  moist,  fire  that  which  was  hot 
and  dry,  and  air  that  which  was  hot  and  moist.  More  elements 
were  added  during  the  Middle  Ages,  so  that  the  ancient  al- 
chemist spoke  of  six  or  seven  different  elements  out  of  which 
all  known  substances  were  imagined  to  be  composed.  Now, 
since  gold,  silver  and  lead,  for  instance,  are  all  composed  of 
the  same  Aristotelian  elements,  it  seemed  natural  that  if  one 
changed  the  proportion  of  these  elements,  lead,  for  instance, 
might  be  converted  into  silver  or  gold. 

To  the  present  time  we  have  retained  the  word  element,  but 
we  have  given  to  it  a  somewhat  altered  meaning,  because  we 
have  recognized  that  some  of  the  substances  thought  by  the 
ancient  and  mediaeval  philosophers  to  be  simple  are  really  com- 
pounds or  mixtures;  while  many  of  the  substances  which  they 
considered  composite  baffle  the  skill  of  the  chemist  when  he 
attempts  to  disintegrate  them.  The  simple  metals  are  now  all 
of  them  considered  as  chemical  elements;  and  we  were  until 
very  recently  apt  to  look  back  with  a  good  deal  of  scorn  upon 
the  alchemists  who  strove  to  change  one  metal  into  another. 


ATOMS  AND  MOLECULES  53 

But  they  were  right  from  their  point  of  view,  just  as  we  are 
right  from  ours,  for  with  the  knowledge  that  coal  tar  contains 
the  elements  carbon,  hydrogen,  nitrogen  and  oxygen,  which 
are  also  contained  in  indigo,  in  quinine  and  in  oil  of  bitter 
almonds  or  in  vanilla,  we  attempt  to  convert  the  coal  tar  into 
one  of  these.  The  difference  is  that  the  alchemists  failed  while 
we  succeed,  and  our  success  is  largely  based  upon  the  experi- 
ence obtained  from  the  unsuccessful  efforts  of  our  predecessors. 
The  other  notion  which  originated  in  Greece  was  that  of  the 
atoms,  out  of  which  all  matter  was  supposed  to  be  composed. 
Democritus  of  Abdera  is  supposed  to  have  invented  the  sug- 
gestion that  all  matter  is  made  up  of  little  particles  which 
have  their  own  separate  existence  and  move  about  freely 
until  they  happen  to  attach  themselves  to  one  another. 
This  idea  occupied  the  attention  of  some  other  Greeks  and 
Romans,  but  during  the  Middle  Ages  it  was  entirely  lost  to 
view;  and  in  fact,  its  real  importance  was  only  recognized 
after  the  already  mentioned  change  had  occurred  in  our  views 
concerning  the  elements.  Now,  under  the  lead  of  John  Dai- 
ton,  we  believe  that  the  finest  particles  of  which  matter  is 
composed  that  we  are  able  to  recognize,  are  little  bodies 
which  cannot  be  decomposed  further  by  ordinary  chemical 
means,  and  which  behave  very  much  as  if  they  were  little 
round  pellets  possessed  of  independent  motion,  and  only  in- 
fluenced by  those  other  little  pellets  that  lie  around  them. 
These  atoms  must  have  very  many  properties  of  their  own, 
and  the  different  atoms  do  not  necessarily  have  the  same 
properties.  When  two  atoms,  therefore,  are  alike  in  their 
properties,  we  call  them  atoms  of  the  same  element;  when  the 
properties  differ,  they  are  atoms  of  different  elements.  Now, 
inasmuch  as  there  are  over  seventy-five  elements  known  to  the 
chemist,  there  must  be  at  least  seventy-five  different  species 
of  atoms.  Whether  these  atoms  are  themselves  made  up  of 


54  MORRIS  LOEB 

seventy-five  different  sorts  of  substances  is  a  question  with 
which  we  cannot  concern  ourselves.  Some  chemists  choose  to 
believe  that  they  are  made  up  of  only  one  sort  of  substance, 
arranged  in  different  fashion  for  each  kind  of  atom,  and  others 
have  ideas  that  are  even  more  difficult  to  grasp  than  this  one. 
But  inasmuch  as  the  chemist  acknowledges  that  he,  at  least, 
cannot  go  further  in  his  subdivision  than  the  atom,  it  is  safe 
for  us  to  stop  there  in  our  study  this  evening.  We  can  never 
expect  to  see  an  atom,  or  to  distinguish  it  by  one  of  our  senses 
from  its  neighbor.  What,  therefore,  the  real,  actual  proper- 
ties of  the  atom  may  be,  is  just  as  hard  for  us  to  conceive,  as 
it  is  to  imagine  how  the  inhabitants  of  some  other  planet 
would  look.  Nevertheless,  if  somebody  tells  us  that  there  are 
inhabitants  of  Mars,  we  straightway  fall  to  imagining  that 
those  Martians  must  look  more  or  less  like  ourselves,  or  like 
something  that  we  see  on  earth.  In  the  same  fashion  we  reason 
by  analogy  concerning  the  atoms,  and  readily  reach  conclu- 
sions concerning  their  general  properties  from  the  behavior  of 
the  substances  which  they  compose.  Nevertheless  I  would 
especially  guard  those  of  you  who  are  interested  in  chemistry 
against  imagining  that  we  really  know  so  very  much  about 
atoms,  although  we  know  a  good  deal  about  the  elements 
after  which  they  are  named. 

Let  us  in  the  first  place  attempt  to  get  some  experimental 
idea  of  the  size  of  *an  atom.  I  take  here  a  red  substance  (the 
well-known  aniline  dye  called  fuchsine)  which  is  made  up,  as 
I  happen  to  know,  of  several  elements;  and  a  very  little  of  it 
gives,  as  you  see,  an  intensely  red  coloration  to  a  little  water. 
If  I  pour  this  small  amount  of  liquid  into  a  measuring  glass, 
and  add  to  it  one  hundred  times  as  much  water,  the  color  is 
still  very  distinct,  and  taking  one-tenth  of  this  and  again 
diluting  it  with  yet  one  hundred  parts  of  water,  you  can  still 
faintly  perceive  the  red  color.  Now  the  original  weight  of  the 


ATOMS  AND  MOLECULES  55 

coloring  matter,  which  covered  only  the  point  of  a  knife,  was 
barely  one  grain;  dispersed  over  the  great  bulk  of  water  which 
you  see  here,  it  nevertheless  retained  its  pink  coloration, 
which  must  be  a  proof  to  you  how  finely  its  substance  is  capa- 
ble of  subdivision  without  being  decomposed.  One  faintly 
pink  drop  of  the  most  dilute  solution  must  contain  at  least  one 
of  the  smallest  particles  of  the  red  fuchsine;  and  each  of  these 
small  particles  or  molecules  must  be  made  up  of  a  number  of 
smaller  particles  or  atoms  of  four  elements,  one  solid  and 
black,  the  three  others  colorless  gases  with  which  you  are 
undoubtedly  familiar,  and  which  make  up  the  important  parts 
of  the  atmosphere  and  of  water.  If  these  four  elements  had 
been  merely  mixed  together,  one  would  separate  at  once,  as 
happens  now  when  I  mix  a  little  carbon  dust  with  air.  Hence 
we  conclude  that  in  the  red  compound  the  carbon,  oxygen,  hy- 
drogen, and  nitrogen  exist  not  as  we  know  them,  but  with  the 
atoms  joined  intimately  together  to  form  a  new  chemical 
compound;  and  it  is  only  when  we  split  this  compound  into  a 
condition  bordering  on  the  fineness  of  the  atoms,  that  we  can 
be  said  to  decompose  it  into  its  constituent  parts.  The  point 
to  which  we  can  reduce  the  compound  before  it  breaks  up  is 
called  the  molecule,  often  defined  as  the  smallest  portion  of 
the  compound  which  can  exist  and  still  retain  the  properties 
of  that  substance.  In  the  dilution  just  shown,  the  molecules 
were  very  widely  separated  and  were  surrounded  by  molecules 
of  water. 

What,  then,  is  the  size  of  a  molecule?  This  is  one  of  the 
most  interesting  problems  that  has  been  put  before  the  physi- 
cist, and  it  is  a  great  triumph  for  science  that  four  or  five 
different  methods  have  been  discovered  for  determining  this 
size,  and  that  the  results  have  been  found  to  agree  tolerably 
well  with  one  another.  We  are  accustomed  to  look  with  more 
awe  on  big  things  than  on  little  ones;  and  so,  when  we  are  told 


56  MORRIS  LOEB 

of  the  distance  between  the  earth  and  the  sun,  or  of  the  great- 
ness of  the  sun's  diameter,  we  exclaim  at  the  magnitude  of  the 
figure,  while  we  talk  unconcernedly  of  molecules.  Is  it,  how- 
ever, so  easy  to  realize  the  exceeding  smallness  of  the  mole- 
cule? 

The  measurement  of  the  magnitude  of  molecules  can  be 
performed  in  the  following  fashion.  As  a  soap  bubble  expands 
with  its  increasing  inflation  its  film  can  be  greatly  stretched. 
The  thin  bubble  becomes  more  and  more  brilliant  in  color  as 
it  grows  thinner;  and  then  a  moment  comes  when  the  film 
suddenly  loses  its  color  and  becomes  black.  This  is  because  a 
certain  thickness  between  the  front  and  rear  wall  of  a  film  is 
required  in  order  that  the  film  shall  show  colors  by  reflection. 
When  it  has  become  colorless,  we  know  that  we  have  stretched 
it  so  that  it  no  longer  possesses  this  requisite  thickness;  it  is 
thinner  than  the  length  of  a  wave  of  light.  In  order  that  it 
should  be  a  continuous  film,  it  must  consist  of  at  least  one 
row  of  molecules;  therefore,  a  molecule  is  less  thick  than  the 
wave  length  of  light  is  long.  Immediately  after  the  film  is 
stretched  to  this  extreme  thinness,  it  breaks,  which  is  a  proof 
to  us  that  there  is  not  so  very  much  difference  between  the 
magnitude  of  the  wave  length  of  light  and  the  molecule. 

Another  interesting  method  of  measuring  the  size  of  a  mole- 
cule is  to  be  derived  from  the  behavior  of  gases  as  they  rub 
upon  one  another,  and  while  this  involves  much  that  could 
not  be  studied  here,  it  suffices  to  say  that  the  same  results  are 
obtained  as  by  the  previous  method.  Still  other,  but  yet  con- 
cordant results  can  be  obtained  from  a  study  of  the  expansion 
of  gases  by  heat,  and  their  contraction  under  great  pressure. 
From  all  these  we  reach  the  conclusion  that  the  molecules 
have  some  real  definite  size,  and  likewise,  that  they  consist  of 
comparatively  few  atoms  apiece. 

In  order  that  we  may  understand  better  what  the  rela- 


ATOMS  AND  MOLECULES  57 

tions  of  atoms  and  molecules  are,  I  now  take  up  some  interest- 
ing experiments  with  substances  that  are  elements;  this  is 
because  we  know  that  when  we  are  dealing  with  a  single  ele- 
ment no  change  will  occur  which  involves  more  than  one  kind 
of  atom.  I  have  here  a  jar  of  the  substance  originally  known  as 
oxygen,  and  the  arrangement  is  such  that  I  am  able  to  pass 
this  oxygen  through  various  pieces  of  apparatus,  illustrating 
properties  of  oxygen.  By  simply  exposing  the  gas  to  a  current 
of  electricity  I  give  to  it  entirely  different  properties,  as  you 
will  see  when  I  pass  a  little  oxygen  over  this  piece  of  paper, 
and  then  expose  a  strip  of  the  same  piece  to  the  action  of  the 
electrified  oxygen,  or  ozone,  as  it  is  called.  You  must  not  sup- 
pose that  there  is  any  electricity  in  this  ozone  which  makes  it 
different  from  the  oxygen.  I  have  here  some  ozone  made  by  a 
totally  different  process,  and  it  shows  the  same  effect.  The 
ozone  can  be  converted  back  into  the  oxygen,  as  you  will  see 
when  I  pass  it  through  this  heated  tube;  it  now  has  lost  its 
power  of  affecting  the  impregnated  paper;  it  has  been  con- 
verted back  into  original  oxygen.  In  fact,  all  our  study  shows 
us  that  the  sole  difference  between  ozone  and  oxygen  consists 
in  the  arrangement  of  the  atoms;  one  molecule  of  oxygen  must 
be  assumed  to  contain  two  atoms,  and  one  molecule  of  ozone 
three  atoms. 

If  this  were  a  single  instance  standing  entirely  by  itself,  the 
opinion  might  be  attacked;  but  we  have  many  similar  cases 
in  chemistry,  although  it  is  not  always  so  easy  to  prove  the 
matter  as  in  the  case  of  the  oxygen.  I  have  here  two  specimens 
of  phosphorus,  which  to  all  appearances  are  entirely  different 
in  their  nature;  the  one  is  a  coherent  yellow  mass,  the  other  is 
a  red  powder;  and  many  of  the  properties  are  different  like- 
wise. This  one  is  poisonous,  that  one  not;  this  one  catches 
fire  with  great  ease,  the  other  will  catch  fire  only  after  consider- 
able heating.  Once  I  have  set  the  two  a-burning,  however,  the 


58  MORRIS  LOEB 

result  of  their  union  with  the  oxygen  of  the  air  is  precisely  the 
same.  The  white,  powdery  oxide  of  phosphorus  forms  in  each 
case,  and  if  I  take  the  same  quantity  of  two  kinds  of  phos- 
phorus, I  shall  have,  in  each  case,  the  same  quantity  of  oxide 
formed.  These  facts  prove  that  the  two  substances  are  identi- 
cal in  composition,  although  probably  differing  in  the  arrange- 
ment of  their  atoms.  It  fact,  it  is  a  common  operation  of  the 
chemical  manufacturer  to  convert  yellow  phosphorus  into 
red,  as  it  merely  requires  heating  under  pressure  to  effect  the 
conversion. 

Here  is  another  element,  sulphur,  which  shows  the  same 
tendency  to  appear  under  different  guises  representing  differ- 
ent arrangements  of  the  atoms.  If  I  melt  sulphur,  it  becomes 
a  thin  liquid;  but  on  heating  further  it  thickens  and  cannot 
be  poured,  even  upon  the  inversion  of  the  test-tube.  Yet  more 
heating  converts  it  yet  again  to  a  liquid;  and  if  I  now  pour 
it  into  water  so  as  to  cool  it  suddenly,  I  obtain  the  sulphur  in 
a  very  remarkable  condition,  appearing  in  many  respects 
like  a  gum;  but  it  is  still  sulphur.  This  might  be  proved  by 
drying  it  and  setting  it  aside  in  a  vessel  entirely  free  from 
all  other  chemical  agencies,  when  it  would  in  time  go  back 
into  the  condition  of  the  yellow  sulphur.  By  kneading  it 
in  my  hands,  I  am  able  to  effect  this  conversion  much  more 
speedily. 

These  and  various  other  cases  of  change  happening  to  a 
simple  substance,  separated  from  other  substances,  force  us  to 
assume  that  the  actual  element  has  undergone  no  change,  but 
that  its  atoms  have  rearranged  themselves  into  new  patterns. 
Such  changes  are  best  suited  to  make  clear  to  you  why  we 
make  the  distinction  between  the  molecules  and  the  atoms. 
Every  substance  that  we  know  of  is  supposed  then  to  be 
made  of  molecules  built  up  of  one  or  more  atoms.  If  the 
molecules  are  broken  up,  or  their  atoms  rearranged,  we  ob- 


ATOMS  AND  MOLECULES  59 

tain  different  kinds  of  molecules,  therefore  different  kinds  of 
substance;  but  the  atoms  are  not  changed  in  the  operation, 
and  we  know  no  method  of  changing  them. 

You  may  well  ask,  how  can  we  get  hold  of  molecules  in 
order  to  study  them?  It  is  impossible  to  catch  a  single  mole- 
cule and  examine  it,  or  even  a  hundred  molecules;  but  we  have 
every  reason  to  believe  that  in  gases  the  molecules  behave 
more  independently  than  they  do  in  liquids  or  in  solids. 
Hence  when  we  wish  to  study  molecules  we  begin  by  studying 
gases.  Imagine  a  big  globe  filled  with  inconceivably  small 
pellets  that  shoot  to  and  fro  in  straight  lines  and  never  come 
to  rest,  and  you  have  a  notion  of  our  conception  of  a  vessel 
filled  with  a  gas.  Whenever  one  of  these  molecules  hits  the 
side  of  the  vessel  it  pushes  against  it  and  tries  to  push  it  out- 
wards; the  sum  total  of  countless  impulses  of  this  kind  is 
supposed  to  constitute  the  pressure  of  a  gas  upon  its  confining 
walls.  If  I  stand  on  a  street  corner  on  a  windy  day,  the  mole- 
cules of  air  strike  my  face,  and  I  feel  this  as  a  direct  pressure 
which  seems  to  me  continuous  because  there  are  so  many 
billions  of  molecules  striking  my  face  in  succession.  The 
more  molecules  there  are  in  a  given  space  of  gas,  the  more 
frequently  they  must  hit  the  walls,  and  the  greater  becomes 
the  pressure.  The  hotter  the  gas  is,  the  livelier  the  molecules 
become;  they  travel  faster;  thus  we  explain  the  fact  that 
heating  increases  the  pressure  of  the  gas  upon  its  confining 
walls. 

In  the  liquid  or  solid  state,  the  molecules  no  longer  travel 
around  freely  in  all  directions,  but  hang  together,  and  occupy 
a  limited  portion  of  the  vessel  into  which  they  are  put,  so  that 
it  is  much  harder  to  know  what  they  are  really  doing.  In  the 
gas  each  molecule  is  supposed  to  be  acting  for  itself,  in  the 
liquid  or  solid  they  must  all  act  together. 

Interesting  evidence  of  the  fact  that  molecules  are  little 


60  MORRIS  LOEB 

independent  bodies  moving  in  a  very  definite  way  and  having 
very  definite  size,  is  found  in  a  well-known  experiment  known 
as  osmose.  Suppose  that  in  this  room  there  was  a  partition 
which  was  pierced  by  a  number  of  narrow  doors,  and  on  the 
one  side  were  a  number  of  grown  persons  and  on  the  other  an 
equal  number  of  children,  and  the  order  was  given  that  they 
should  distribute  themselves  equally  over  the  total  space. 
The  children,  moving  more  quickly,  and  having  no  difficulty 
in  squeezing  through  the  narrow  doors,  would  soon  get  over 
to  the  other  side,  while  the  grown  persons  were  still  struggling 
to  get  through.  The  result  would  be  that  at  first  the  actual 
number  of  people  on  that  side  of  the  room  where  the  children 
had  first  been  would  be  less  than  the  number  on  the  other 
side.  Now,  instead  of  persons,  I  take  light  and  heavy  mole- 
cules, the  lightest  molecules  we  know  being  hydrogen,  and  the 
molecules  constituting  the  gases  of  the  air  being  over  fourteen 
times  as  heavy.  In  order  to  imitate  the  partition  wall,  I  take 
this  tube  made  of  porous  porcelain;  the  openings  are  so  fine 
that  we  may  well  imagine  the  gas  molecules  having  some  trouble 
in  getting  through.  If  I  fill  the  inside  of  this  tube  with  air, 
and  now  fill  this  jar  outside  with  hydrogen,  the  hydrogen  will 
get  in  very  much  faster  than  the  air  can  get  out,  and  the  result 
will  be  that  we  have  a  larger  number  of  particles  or  molecules 
per  cubic  inch  inside  than  there  were  originally;  they  have 
to  find  more  room  for  these,  and  you  see  how  they  obtain  it, 
by  pressing  this  liquid  out  in  a  sort  of  fountain.  If  I  reverse 
the  experiment,  I  obtain  the  opposite  effect.  There  is  a  rather 
ingenious  practical  application  of  this  principle  which  is  per- 
haps worth  showing.  Instead  of  holding  water  to  be  pressed 
out,  this  tube  contains  mercury;  as  the  liquid  metal  is  pressed 
down  it  will  rise  on  the  opposite  side  and  make  an  electric 
contact,  which  causes  this  bell  to  ring.  Instead  of  taking 
hydrogen  I  shall  this  time  take  illuminating  gas,  —  and  here 


ATOMS  AND  MOLECULES  61 

you  see  how  soon  an  alarm  is  given.  Such  an  arrangement 
might  well  be  used  where  a  dangerous  or  harmful  gas  is  apt  to 
appear;  it  was  really  invented  for  coal  mines,  in  which  there 
is  a  danger  of  the  formation  of  explosive  mixtures  of  lighter 
combustible  gases  with  air. 

In  this  way  it  is  possible  to  distinguish,  as  you  see,  between 
lighter  and  heavier  molecules.  This  method  may  be  of  value 
to  the  investigator,  as  we  shall  see.  I  have  here  a  substance 
whose  molecules  are  fairly  large;  they  are  ordinarily  in  a  solid 
state,  and  they  represent  a  substance  which  is  neutral,  as  we 
say  in  chemistry,  —  a  salt  that  has  no  effect  upon  vegetable 
colors.  I  throw  a  little  of  it  upon  these  pieces  of  red  and  blue 
litmus  paper,  and  you  see  that  there  is  no  change.  Now  a 
piece  of  this  salt  (which  we  call  chloride  of  ammonium)  is 
placed  in  this  glass  tube  next  to  a  porous  partition  wall;  when 
I  warm  the  salt  it  breaks  up  into  two  substances  called  am- 
monia and  hydrochloric  acid,  which  may  be  separated  by  the 
method  of  osmosis  just  used  to  ring  an  electric  bell.  The 
ammonia  consists  of  molecules  so  light  that  it  passes  very 
readily  through  this  partition  wall,  while  the  hydrochloric 
acid  with  heavier  molecules  passes  less  readily.  You  will  be 
able  to  notice  this  when  I  pump  air  through  both  parts  of  the 
apparatus  and  let  the  two  currents  of  air  flow  over  these  two 
pieces  of  colored  paper.  You  see  how  the  red  paper  is  turning 
blue,  and  the  blue  paper  is  turning  red;  this  is  due  to  the  fact 
that  the  hydrochloric  turns  blue  paper  red  and  more  of  it  re- 
mains on  the  near  side  of  the  partition;  the  ammonia  turns 
red  paper  blue,  and  more  of  it  has  gone  through  the  partition. 
The  experiment  not  only  illustrates  to  you  what  I  have  shown 
before  in  a  somewhat  different  form,  but  it  also  shows  us  that 
the  big  molecules  of  chloride  of  ammonia  can  be  broken  up 
into  two  sets  of  smaller  molecules,  which  themselves  differ 
from  one  another  in  size.  We  can  even,  although  I  am  unable 


62  MORRIS  LOEB 

to  show  it  here,  break  up  this  hydrochloric  acid  and  this 
ammonia  into  still  smaller  molecules,  and  beyond  these  still 
are  supposed  to  be  the  atoms.  Every  rearrangement  of  atoms 
into  molecules  produces  a  new  substance,  and  it  is  the  marvel- 
ous ability  of  the  atoms  to  arrange  themselves  into  hundreds 
of  thousands  of  ways  that  enables  the  organic  chemist  to 
build  up  out  of  three  or  four  elements  the  many  compounds 
which  nature  is  building  up  for  us  daily  and  hourly  in  plants 
and  animals. 

Such  then,  is  the  idea  entertained  by  the  chemist  of  to-day 
concerning  the  nature  of  the  mechanism  carrying  out  the 
changes  which  it  is  his  business  to  study.  But  we  must  re- 
member that  this  idea  is  hypothetical  —  it  is  no  more  than  a 
plausible  guess.  While  the  few  master-minds  of  a  century 
can  grasp  such  theories  as  pure  abstractions,  uninfluenced  by 
preconceived  notions,  the  rest  of  us  cannot  free  ourselves  of 
the  prejudices  derived  from  the  familiar  phenomena  upon 
which  the  theories  are  based.  We  are  as  little  able  to  strip  our 
imagined  infinitesimal  particles  of  Matter  and  Energy  from 
the  attributes  of  the  grosser  masses  of  our  daily  observation, 
as  was  the  Greek  to  impart  other  than  human  qualities  to  his 
gods,  whom  he  portrayed  in  human  form.  This  is  one  of  the 
reasons  for  the  many  more  or  less  fantastic  attempts  to  over- 
turn the  atomic  theory  as  it  now  exists.  I  do  not  believe  that 
the  theory  is  perfect  or  ultimately  correct,  but  a  study  of 
most  of  the  attacks  upon  it  leads  to  the  conclusion  that  the 
attack  is  made,  not  upon  the  pure  theory,  but  upon  that  par- 
ticular image  which  has  been  set  up  to  represent  the  theory 
in  an  iconoclast's  intellectual  neighborhood.  Thus  we  some- 
times find  persons  who  imagine  they  are  attacking  the  atomic 
theory,  when  they  contend  only  against  the  gratuitous  idea 
that  'atoms  are  hard,  round  pellets,  rather  than  vortices  of 
an  infinitely  elastic  fluid  or  the  like.  But  we  have  no  time 


ATOMS  AND  MOLECULES  63 

to-night  for  these  objections  and  criticisms,  —  it  is  enough  if  I 
have  succeeded  in  giving  you  some  idea  of  what  the  chemist 
means  by  atoms  and  molecules,  and  how  these  conceptions 
help  him  to  explain  and  understand  the  intricate  and  subtle 
processes  of  chemical  reaction. 


HYPOTHESIS  OF  RADIANT  MATTER1 

THE  enormous  literature  which  has  developed  from  the 
discovery  of  radium  and  from  the  study  of  cognate  pheno- 
mena has  made  it  increasingly  difficult  to  form  a  calm 
opinion  upon  the  merits  of  all  the  claims  which  have  been 
advanced,  and  upon  the  validity  of  the  theories  which  have 
been  based  upon  them.  Undoubtedly,  the  great  bulk  of  the 
experimental  data  is  exact,  although  time  may  show  that 
some  of  the  results  which  were  recorded  before  the  technique 
was  fully  developed  may  require  correction.  Without  ques- 
tioning in  the  slightest  degree  the  experiments  reported 
by  some  of  the  skillful  observers  of  modern  times,  one  is, 
nevertheless,  permitted  to  hesitate  in  adopting  hypotheses 
that  not  only  subvert  formerly  accepted  ideas,  but  also  seem, 
in  many  cases,  inconsistent  with  one  another. 

The  chemical  world  has  been  accused  of  accepting  too  dog- 
matically the  theory  of  the  conservation  of  matter,  the  in- 
divisibility of  the  atom,  etc.  Ought  we  not,  then,  to  guard 
ourselves  against  a  similar  fault  in  adopting  newer  views? 

I  propose  to  take  up  seriatim  the  methods  of  reasoning 
which  have  led  to  the  present  hypothesis  of  radiant  matter 
as  expressed  by  its  chief  exponents,  and  to  indicate  some 
points  which  seem  to  me  to  be  inconsistent  with  older  views, 
or  in  conflict  with  one  another;  and  I  shall  begin  with  what 
may,  from  the  present  point  of  view,  be  called  a  static 
phenomenon,  the  behavior  of  the  atom  toward  light.  It  is 
known  that  Lorentz  modified  Maxwell's  electro-magnetic 

1  Extracts  from  a  review  presented  to  the  New  York  Section  of  the  American 
Chemical  Society  at  its  meetings,  November,  1907,  and  published  in  The  Popular 
Science  Monthly,  73,  p.  52,  July,  1908.  Reprinted  by  permission. 


HYPOTHESIS  OF  RADIANT  MATTER     65 

theory  of  light,  by  assuming  that  the  vibrations  from  which 
light-waves  originate  are  not  produced  by  the  atom  as  a 
whole,  but  rather  by  the  vibration  of  its  positive  or  negative 
electric  charge  conceived  as  a  special  entity,  which  we  may 
now  personify,  as  it  were,  by  the  more  recently  coined  name 
"  electron."  The  electron  vibrates  in  an  elliptical  path  which 
is  really  the  result  of  two  circular  oscillations  in  opposite 
directions,  and  of  differing  amplitudes, but  of  identical  period. 
An  alteration  of  the  radii  of  these  circles  would  merely  alter 
the  shape  of  the  ellipse;  but  if  the  periods  of  the  two  circular 
motions  were  made  to  differ,  no  single  resultant  could  appear, 
for  the  two  vibrations  would  produce  waves  of  different  length, 
i.e.,  light  rays  of  different  refrangibility.  Now,  a  magnetic 
strain  ought  to  exert  some  influence  on  an  electron;  if  it 
accelerated  its  dextrogyratory  motion,  it  would  retard  its 
laevo-gy ration,  or  vice  versa.  This  is  precisely  what  Zeeman 
found  when  he  examined  the  emission-spectra  of  vapors  that 
were  placed  in  an  electromagnetic  field;  single  lines  are  broken 
up  into  two  or  more  finer  lines,  placed  symmetrically  with 
regard  to  the  position  of  the  original  one.  Righi  has  general- 
ized the  reasoning  so  that  it  covers  practically  every  relation 
between  the  vibrating  electron  and  the  external  magnetic 
strain  to  which  it  is  subjected,  and  reaches  two  conclusions: 
First,  the  vibrating  electron  is  electro-negative;  second,  the 
ratio  e/m,  i.e.,  electric  charge  over  mass,  is  about  1000  times 
as  great  as  the  ratio  between  the  electric  charge  and  mass 
of  the  hydrogen  ion.  Assuming,  perhaps  arbitrarily,  that  the 
electric  charge  is  the  same,  the  mass  of  the  electron  is  about 
1/1000  that  of  the  hydrogen  ion;  it  can  be  no  mere  coinci- 
dence that  Thomson,  Kaufmann,  and  others  arrive  at  vir- 
tually the  same  figure  for  the  mass  of  the  corpuscles  which 
carry  the  negative  charges  in  ionized  gases  of  whatever  chemi- 
cal constitution;  in  fact,  everybody  recognizes  their  identity. 


66  MORRIS  LOEB 

To  quote  Righi,  the  neutral  chemical  atom  (as  distinguished 
from  the  ion)  consists  of  a  central  mass  of  positive  charge, 
around  which  revolve  as  satellites  one  or  more  electro- 
negative corpuscles,  retained  in  their  orbits  by  some  centrip- 
etal force. 

In  connection  with  this  definition,  the  following  points 
seem  to  require  emphasis:  the  number  of  electrons  per  atom 
are  few,  practically  corresponding  to  the  valency;  this 
seems  to  be  corroborated  by  recent  experiments  of  Becquerel 
on  the  phosphorescence  of  uranium  minerals  at  low  tempera- 
tures, which  likewise  point  out  that  light-emission  is  not 
always  confined  to  the  negative  corpuscle,  as  Righi  would 
have  it.  The  total  mass  of  the  free  electrons  in  an  atom  is 
not  sufficient  to  affect  the  ratio  between  specific  heats  for  con- 
stant pressure  and  constant  volume  of  monatomic  vapors, 
like  mercury  and  cadmium;  their  velocity  in  their  orbits  does 
not  approach  that  of  light,  and  they  have  no  high  momentum 
retained  by  comparatively  powerful  internal  attractions. 
These  electrons  can  not  be  identical  with  the  X-particles 
which  are  projected  with  terrific  force  from  the  uranium, 
radium  and  other  atoms,  according  to  Rutherford  and  his 
followers. 

I  need  only  touch  briefly  on  the  electric  discharges  in  vac- 
uum tubes:  it  is  generally  accepted  that  we  distinguish 
Lenard  or  cathode  rays,  which  are  negative,  and  positive 
Goldstein  or  canal  rays  within  the  tube.  They  can  be  de- 
flected by  electric  or  magnetic  fields,  they  produce  mechani- 
cal and  heating  effects,  cast  visible  shadows,  etc.,  and  they 
behave  in  general  like  streams  of  actual  particles  charged 
with  electricity.  When  the  cathode  ray  strikes  an  impene- 
trable obstacle,  like  glass,  the  X-rays  are  produced  as  a  sec- 
ondary effect:  these  do  not  behave  as  if  conveyed  by  neutral 
particles;  have  vast  penetrating  power;  contain  no  electric 


HYPOTHESIS  OF  RADIANT  MATTER      67 

charge,  as  they  are  not  influenced  by  magnetic  or  electric 
fields,  and  are  neither  refracted  nor  reflected.  Ijwould  em- 
phasize, however,  their  ability  to  discharge  an  electrometer, 
as  well  as  to  influence  the  photographic  plate.  Their  peculiar- 
ities have  been  recently  ascribed  to  the  fact  that  they  repre- 
sented aperiodic  impulses  given  to  the  luminiferous  ether 
—  which  conveys  no  meaning  to  my  mind,  excepting  that  they 
can  not  be  explained  by  the  undulatory  theory.  The  velocity 
of  the  canal  rays  has  been  determined,  and  the  mass  of  their 
hypothetical  particles  measured  by  the  amount  of  their  de- 
flection in  magnetic  fields  of  varying  strength;  both  values 
approximate  those  found  for  the  ordinary  chemical  atoms 
or  molecules;  in  the  case  of  the  negative  cathode  rays,  how- 
ever, the  velocities  and  mass  correspond  to  those  assumed 
for  the  electrons.  I  confess  to  a  serious  difficulty  in  harmon- 
izing the  notion  of  a  corpuscular  structure  of  the  atoms  with 
the  explanation  given  by  the  same  school  for  the  need  of 
high  vacua  for  the  production  of  cathode  rays.  It  is  said 
that  the  electrons  must  have  a  considerable  free  path  in  order 
that  they  may  travel  with  undiminished  velocity  toward  the 
anode:  but  if  the  atoms,  instead  of  being  compact  elastic 
bodies,  be  mere  nebulae  of  electrons,  the  relation  of  whose 
sizes  and  interstices  is  comparable  to  that  of  the  molecules 
in  a  normal  gas,  it  follows  that  a  free  electron,  hurled  vehe- 
mently forward  from  the  cathode,  could  pass  quite  through 
a  number  of  atoms  without  collision  with  any  of  their  con- 
stituent corpuscles;  the  free  path  of  the  electron  is  so  enor- 
mous, on  this  hypothesis,  that  the  order  of  its  magnitude 
could  not  be  materially  affected  by  the  degree  of  rarefaction 
of  the  gas  customary  in  the  Crookes  tube. 

We  must  recollect,  however,  that  the  hypothesis,  first 
elaborated  by  Larmor,  that  the  electrons  are  the  primordial 
constituents  of  the  atoms,  does  not,  like  that  of  Prout, 


68  MORRIS  LOEB 

simply  extend  the  limits  of  the  divisibility  of  matter.  The 
electron  is  not  to  be  considered  as  a  small  speck  of  matter  at 
all,  but  as  a  permanent  manifestation  of  energy  concentrated 
on  a  minute  portion  of  the  luminif erous  ether.  The  view  and 
the  explanation  of  many  phenomena  on  such  a  basis  has  been 
acclaimed  as  the  triumph  of  energetics,  the  final  elimination 
of  the  conception  of  matter.  An  unbiased  reading  of  J.  J. 
Thomson's  Yale  lectures,  however,  will  impress  anybody 
that  he  decidedly  materializes  both  energy  and  ether.  Per- 
haps much  of  this  materialization  is  purely  symbolic,  to  bring 
his  mathematical  reasoning  within  the  comprehension  of  his 
audience;  but  to  me  it  seems  that  an  electric  charge  which 
has  quantity,  mass,  inertia,  elasticity,  and  expansibility,  which 
obeys  the  laws  of  hydrostatics,  and  virtually  has  a  surface 
beyond  which  it  can  only  produce  effects  by  the  medium  of 
mysterious  lines  of  force,  has  a  marvelous  resemblance  to  the 
picture  which  the  ordinary  chemist's  mind  would  form  of 
material  substance.  His  ether  is  not  only  that  puzzling  para- 
dox, at  once  impalpable  and  inconceivably  dense,  rigid  and 
frictionless,  which  we  have  accepted  as  the  whole  means  of 
explaining  the  transmission  of  motion  through  a  vacuum; 
to  extend  its  importance  as  the  substratum  of  all  phenomena 
it  must  become  heterogeneous  and  capable  of  deformation; 
to  form  a  neutral  atom,  some  of  it  must  become  a  spherical 
jelly  in  which  other  parts  of  itself  are  imbedded  as  rigid  par- 
ticles. It  has,  consequently,  different  degrees  of  hardness, 
and  is  subject  to  internal  attractions.  Thomson  even  volun- 
teers the  admission  that,  for  the  explanation  of  certain 
phenomena,  his  ether  must  have  structure,  or,  at  least,  be 
stratified. 

This  can,  of  course,  be  no  insinuation  against  the  work  of 
some  of  the  greatest  living  physicists  and  mathematicians: 
accepting  their  premises,  I  do  not  doubt  that  they  have 


HYPOTHESIS  OF  RADIANT  MATTER      69 

drawn  the  consequences  in  the  most  rigid  fashion.  I  do  assert, 
however,  that  some  of  their  fundamental  terms  are  used  in  a 
different  sense  from  that  to  which  we  are  accustomed,  and 
that  we  are,  therefore,  entitled  to  doubt  whether  the  con- 
clusions which  they  reach  really  affect  the  phenomena  with 
which  the  chemist  deals:  as  if  one  were  to  discuss  the  crystal- 
lographic  structure  of  Pentelian  marble  with  reference  to  the 
architecture  of  the  Parthenon. 

A  few  examples,  pertinent  to  our  inquiry,  will  more  pre- 
cisely establish  my  meaning.  One  of  the  fundamental  postu- 
lates of  Professor  Thomson's  mathematical  argument  is  the 
definition  of  momentum  as  the  product  of  mass  by  velocity. 
Although  this  is  not  axiomatic,  we  accept  it  as  such  by  reason 
of  the  many  ballistic  experiments  which  have  proved  its  truth, 
so  long  as  the  projectile's  mass  was  assumed  to  remain  con- 
stant: we  should  hesitate  if  we  were  told  that  mass  was  to 
vary,  i.e.,  that  a  bullet  which  weighs  the  same  before  and  after 
the  shot,  was  heavier  during  its  flight.  But  the  momentum 
of  Thomson's  electrons  increases  faster  than  their  velocity, 
when  the  latter  approaches  that  of  light;  hence,  he  says,  the 
mass  of  the  electrons  increases  with  their  swiftness.  True,  he 
calls  it  an  electro-magnetic  mass,  but  some  of  his  followers 
have  forgotten  the  distinction.  At  all  events,  his  terms  "  mo- 
mentum "  and  "  mass  "  must  not  be  accepted  by  us  in  their 
usual  meaning. 

It  is  perfectly  true  that  Thomson's  calculations  are  corrob- 
orated by  Kaufmann's  experiments  on  the  velocity  of 
radium  rays  in  combined  electric  and  magnetic  fields,  if  the 
latter 's  data  are  calculated  according  to  Thomson's  views; 
without  even  seeking  a  radically  different  basis  —  which 
would  not  be  difficult  —  we  can  follow  Thomson  to  a  point 
where  his  departure  from  ordinary  assumptions  becomes  evi- 
dent. He  shows  that  the  value  elm  diminishes  at  high  veloc- 


70  MORRIS  LOEB 

ities  and  then  he  assumes  that  e>  the  electrostatic  charge, 
is  constant;  therefore  m,  the  mass,  varies.  Now,  the  value 
of  e  is  derived  from  Faraday's  law,  which  would  never  have 
been  announced  if  Faraday  had  not  dealt  with  the  equivalent 
weights  as  fixed  mathematical  quantities.  In  fact,  just  so 
far  as  Thomson  substantializes  electricity  by  giving  it  atomic 
structure,  with  invariable  mass,  the  chemical  atom  becomes 
wavy  and  matter  evanesces  into  the  ghost-like  form  which 
energy  has  assumed  in  the  chemical  mind.  If  our  scientific 
terms  are,  as  it  were,  to  receive  the  reciprocals  of  their  present 
significance  —  progress  may  ultimately  result,  but  we  should 
enter  into  topsy-turvy dom  with  our  eyes  open. 

The  electron  theory  possesses  the  merit  of  furnishing  a 
working  hypothesis  upon  which  to  coordinate  the  various 
electrical  phenomena  of  vacuum  tube  and  radio-active  origin : 
chief  among  which  is  the  increased  conductivity  of  gases. 
Either  direct  current  measurement  or  the  more  sensitive 
electrometer,  determinative  of  the  decrease  of  electrostatic 
potential,  indicates  that  gases  begin  to  conduct  electricity 
when  affected  by  ultra-violet  light,  by  cathode  and  X-rays, 
by  radium,  thorium,  etc.  Ingenious  experiments  have  proved 
that  portions  of  the  gas  are  positively,  others  negatively, 
charged;  that  they  behave  as  if  ionized;  the  numbers,  masses 
and  charges  of  the  hypothetical  ions  have  been  measured  and 
found  to  agree  with  the  assumption  that  the  negative  ions 
have  the  magnitude  of  the  electrons,  the  positive  ions  that  of 
the  regular  molecules,  i.e.,  the  negative  ions  are  always  very 
small  and  mobile,  with  the  same  value  for  all  gases;  the  posi- 
tive ions  are,  at  least,  1000  times  as  large,  and  vary  for  dif- 
ferent gases.  If  the  gas  moves  away  from  the  locality  of  ion- 
izing influence,  its  conductivity  disappears  gradually  at  a  rate 
to  suggest  reunion  of  the  ions.  Plausible,  if  not  quite  conclu- 
sive, reasoning  connects  the  ionization  hypothesis  with  the 


HYPOTHESIS  OF  RADIANT  MATTER    71 

novel  phenomenon  of  the  saturation  constant;  viz.,  the  fact 
that  the  flow  of  electricity  through  a  conducting  gas  increases 
proportionately  to  the  voltage  between  the  electrodes  up  to 
a  maximum,  when  further  increase  of  potential  has  practically 
no  effect  on  the  current.  This  saturation  current,  it  may  be 
remarked,  is  used  to  characterize  radioactivity;  it  is  admit- 
tedly a  complex  phenomenon,  and  I  should  be  inclined  to  lay 
more  stress  upon  the  qualitative  than  the  precise  quantita- 
tive results  obtained  in  a  number  of  recent  experiments. 

Those  who,  like  Armstrong,  oppose  the  electrolytic  dis- 
sociation hypothesis  of  Arrhenius,  naturally  attack  the  ioni- 
zation  hypothesis  with  still  greater  vehemence,  and  I  believe 
that  this  will  be  the  battleground  of  opposing  theories  for 
some  time  to  come.  As  the  phenomenon  is  distinctly  a  sec- 
ondary reaction,  from  our  point  of  view,  we  need  not  discuss 
it  in  its  various  aspects,  beyond  noting  that  even  without 
detectable  radioactive  agencies  the  atmospheric  air  conducts 
electricity  to  a  slight  extent,  varying  with  location,  as  well  as 
with  the  hours  of  the  day. 

The  radiations  from  the  active  chemical  substances  present 
a  very  complex  aspect;  besides  light  and  heat,  radium  and 
its  congeners  send  out  a-,  J3-,  and  7-rays,  respectively  elec- 
tro-positive, electro-negative  and  neutral  when  tested  in  elec- 
tric and  magnetic  fields. 

From  radium  a-rays  are  sent  out  about  four  times  as  abun- 
dantly as  /3-rays,  the  7  variety  being  relatively  few.  a-rays 
are  electro-positive,  have  a  speed  one  tenth  of  the  velocity 
of  light,  and  a  molecular  mass  of  atomic  magnitude.  They 
penetrate  a  few  centimeters  into  air,  pass  through  thin 
aluminum  foil  but  are  stopped  by  denser  metals.  As  they 
are  but  slightly  deviable  in  a  magnetic  field,  their  momen- 
tum is  calculated  to  be  enormous;  until,  however,  better  evi- 
dence of  the  total  positive  charge  which  they  carry  has  been 


72  MORRIS  LOEB 

obtained,  we  cannot  consider  the  magnitude  of  the  momen- 
tum as  definitely  established;  especially  since  their  speed 
does  not  appear  to  be  uniform.  From  experiments  wherein 
a  particles  are  allowed  to  escape  freely,  and  again  restrained 
by  a  lead  cylinder  surrounding  radium,  much  of  the  appar- 
ent heat  of  the  latter  body  appears  to  be  due  to  the  impinging 
of  the  a-rays  upon  the  surrounding  surfaces. 

/3-rays  are  similar  to  cathode  rays;  they  are  less  absorb- 
able  than  the  a  variety,  and  proceed  at  various  speeds,  many 
approaching  the  velocity  of  light;  they  are  stopped  by  solids 
in  proportion  to  their  density. 

7-rays  are  similar  to  X-rays,  of  great  penetrating  power, 
and  they  are  thought  by  some  to  be  secondary  effects  of  a- 
and  /3-rays,  just  as  the  X-rays  originate  from  the  impact  of 
cathode  rays  on  the  glass  wall  of  the  Crookes  tube.  Besides, 
we  have  a  multitude  of  conflicting  accounts  of  secondary 
tertiary  rays,  resulting  from  these  three  varieties. 

The  chief  method  of  research  is  the  study  of  ionization, 
with  the  interposition  of  screens  and  magnetic  fields,  to 
separate  the  different  kinds  of  rays.  On  the  other  hand,  the 
varieties  of  rays  emitted,  their  relative  strength,  and  their 
variations  of  intensity,  are  the  characteristics  upon  which 
the  identification  of  the  various  so-called  transformation- 
products  of  radioactive  material  is  based.  I  have,  therefore, 
copied  from  Professor  Rutherford's  book 1  tabulations  of  these 
properties. 

With  regard  to  these  various  transformations,  we  should 
realize  that  the  majority  of  the  names  are  titles  of  hypothet- 
ical substances  whose  existence  within  certain  mixtures  is 
assumed  upon  the  evidence  of  their  momentary  radioactiv- 
ity. The  only  one  really  isolated  is  that  emanation  which  has 
all  the  properties  of  a  gas,  including  that  of  condensibility 

1  Radioactivity,  1905. 


HYPOTHESIS  OF  RADIANT  MATTER    73 

at  low  temperatures  —  with  the  exception  that  its  liquid 
form  shows  no  vapor  pressure  —  but  has  in  addition  remark- 
able energy  effects,  and  has,  undoubtedly,  undergone  trans- 
formation in  Ramsay's  hands.  Bearing  in  mind  the  infinitesi- 
mal quantities  of  emanation  which  Ramsay  and  his  associates 
could  obtain,  we  are  alike  astounded  by  their  marvelous 
manipulative  dexterity  and  by  the  nature  of  their  observa- 
tions. First  we  had  the  gradual  appearance  of  helium,  when 
the  emanation  was  stored  by  itself;  then  came  the  appearance 
of  neon,  when  the  emanation  came  into  contact  with  water, 
the  latter  being  partially  decomposed  into  oxygen  and  hydro- 
gen; lastly  the  partial  reduction  of  copper  nitrate  solution, 
with  the  simultaneous  appearance  of  lithium,  while  the  ema- 
nation underwent  a  change  into  argon.  The  lithium,  we  are 
assured/ could  not  be  found  in  the  original  materials;  it  repre- 
sents about  .01  per  cent  of  the  sodium  and  calcium  found  in  the 
same  experiment;  its  actual  amount,  after  correcting  a  slight 
oversight  in  Ramsay's  estimate,  would  be  0.00000003  gram. 
For  such  a  quantity  the  amount  of  copper  transformed  would 
be  too  minute  for  the  detection  of  a  loss  from  the  0.3  gram 
of  copper  which  the  original  solution  may  be  assumed  to  have 
contained:  but,  until  a  loss  of  copper  be  ascertained,  to  corre- 
spond with  the  gain  in  lithium,  it  appears  to  me  that  the  as- 
sumption of  transformation  is  premature.  Ramsay  found  that 
this  solution  contained  in  all  1.67  mg.  alkaline  chlorides, 
chiefly  sodium  chloride;  while  0.79  mg.  was  produced  in  a 
blank  experiment,  when  the  emanation  was  excluded.  While 
this  latter  amount  is  admittedly  derived  from  the  glass  bulb, 
the  excess  obtained  in  the  presence  of  emanation  is  ascribed 
to  the  degradation  of  the  copper,  neglecting  the  fact  that  this 
second  solution  must  have  been  fairly  acid  and  would,  there- 
fore, have  attacked  the  glass  more  vigorously.  Accepting  his 
suggestion,  however,  the  deficit  of  copper  ought  to  approach 


74 


MORRIS  LOEB 


TRANSFORMATION  PRODUCTS  OF  THORIUM,  ACTINIUM,   AND 
RADIUM  ACCORDING  TO  RUTHERFORD 


Product 

Time  to  be  half  transformed 

Radiations 

Thorium 



a-rays 

1 

Th.X 

4  days 

a-rays 

I 

Emanation 

54  seconds 

a-rays 

I 

Thorium  A 

11  hours     ^ 

no  rays 

1  >*33 

Thorium  B 

55  minutes  J 

«-.  /3-»  7-rays 

i 





Actinium 

p 

no  rays 

Actinium  X 

10.2  days 

a  (0  and  7) 

Emanation 

3.9  seconds 

a-rays 

Actinium  A 

35.7  minutes 

no  rays 

Actinium  B 

2.15  minutes 

a,  /3,  and  y 

Radium 

1,200  years 

a-rays 

I 

Emanation 

3.8  days 

a-rays 

i 

• 

Radium  A  J  "o  « 

3  minutes 

a-rays 

Radium  B    ?  3 

21  minutes 

no  rays'* 

Radium  C  J  < 

28  minutes 

o-,  6-,  7-rays 

i 

Radium  D    *s  w> 

about  40  years 

no  rays 

i            1-5 

Radium  E    w  ^ 

6  days 

/3-  (and  "y-)rays 

1                    2   0 

*            '-§53 
Radium  F  J  .§  «g 

143  days 

a-rays 

i 

HYPOTHESIS  OF  RADIANT  MATTER    75 

0.8  mg.,  an  amount  which  ordinary  analysis  can  detect.  We 
may,  therefore,  hope  that  further  experiments  by  Professor 
Ramsay  will  throw  light  upon  this  side  of  the  subject. 

Of  Ramsay's  present  conclusion,  the  following  resume  may 
be  given:  Emanation  is  a  gas  of  about  atomic  weight  216.5, 
derived  from  radium,  of  atomic  weight  225,  simultaneously 
with  a-particles  which  are  not  helium.  When  emanation  and 
the  a-particles  are  shut  up  together,  the  bombardment  of 
the  latter  breaks  up  the  emanation  into  helium;  but  if  heavier 
molecules,  like  water,  be  present,  they  receive  some  of  the 
bombardment,  and  the  emanation  is  only  degraded  into 
neon;  the  pressure  of  copper  nitrate  still  further  protecting 
the  emanation,  so  that  it  only  breaks  down  to  argon.  This 
kinetic  explanation  is  not  impeccable;  for,  according  to  the 
principles  of  mass-action,  the  preponderance  of  water  mole- 
cules in  the  copper  nitrate  solution,  as  well  as  the  predomi- 
nance of  hydrogen  and  oxygen  in  its  decomposition  products, 
would  imply  the  presence  of  considerable  amounts  of  neon  to 
accompany  the  argon.  As  neon  is  said  to  be  absent,  we  must 
either  seek  some  other  hypothesis  or  explain  how  the  neon 
reverts  to  argon  after  it  is  once  formed. 

Ramsay's  views  contradict  those  of  Rutherford  and  others, 
who  seek  to  identify  helium  with  the  a-rays,  and  the  latter 
would  thereby  lose  a  good  deal  of  their  substantive  character. 
Furthermore,  it  is  to  be  noted  that  the  a-particles  bear  posi- 
tive charges:  if  they  were  merely  chemical  atoms,  such  a 
charge  might  possibly  be  obtained  as  they  tore  themselves 
loose  from  the  larger  complex,  during  radiation;  but  if  they 
be  non-substantive  masses  of  free  energy,  it  will  be  difficult 
to  reconcile  the  various  assumed  transformations  with  the 
electro-chemical  properties,  valencies,  etc.,  of  the  elements 
in  question. 

It  must  be  recalled  that  Rutherford  does  assume  that  the 


76  MORRIS  LOEB 

successive  transformations  of  radium,  for  instance,  are  ef- 
fected by  the  expulsions  of  the  a-particles  and  that  these  have 
atomic  mass:  an  atom  of  radium,  therefore,  contains  a  finite 
number  of  them.  As  the  transformations  are  atomic  and 
not  molecular,  Rutherford's  application  of  the  mathematics 
of  mass-action  can  mean  but  one  thing:  that  the  various  rates 
of  transformation  depend  upon  the  chances  of  encounter 
and  relative  positions  of  the  particles  within  the  atom.  These 
rates,  however,  as  measured  by  the  period  of  decay,  vary  from 
thousands  of  years  to  a  few  seconds  for  the  different  educts, 
and  that  irregularly  in  the  order  of  transformation  —  such 
great  differences  could  only  be  explained  by  an  infinite  number 
of  components,  with  large  free  paths, — in  other  words,  elec- 
trons. It  would  then  remain  to  be  shown  what  caused  a 
certain  great  number  of  negative  electrons  to  form  an  electro- 
positive a-particle,  and  become  expelled  with  great  violence 
from  their  surroundings. 

Naturally,  the  failure  of  an  hypothesis  to  explain  certain 
facts  does  not  invalidate  the  latter.  Rutherford's  brilliant 
analysis  of  the  curves  of  increasing  and  decreasing  ionization 
and  the  agreement  observed  with  calculated  results  prove  that 
he  is  not  dealing  with  mere  fortuitous  coincidences.  Many  of 
his  conclusions  seem  incontrovertible  upon  his  premises; 
but  here  again,  the  advocatus  didboli  must  step  in  and  ask 
whether  the  premises  are  axiomatic:  two  of  them  appear  to 
me  to  be  doubtful.  (1)  A  curve  of  decay  is  based  on  electro- 
scopic  measurements  upon  the  tacit  assumption  that  the  rays 
sent  out  by  that  particular  phase  are  always  the  same;  but  we 
are  told  that  both  a-  and  /3-rays  vary  greatly  in  speed  and 
momentum,  hence  neither  variety  would  show  a  uniform  ion- 
izing power;  assuming  that  a  substance  did  send  out  a-rays 
for  a  long  time,  but  that  their  velocities  were  gradually  re- 
duced, would  not  the  ionization  indicate  a  more  rapid  decay 


HYPOTHESIS  OF  RADIANT  MATTER      77 

than  was  really  the  case?  (2)  It  is  practically  assumed 
throughout  that  ionization  is  directly  proportioned  to  the 
amount  of  radio-active  material  present:  but  this  remains  to 
be  proved.  Where  layers  of  any  density  are  involved,  we 
know  that  it  is  not  true,  owing  to  internal  absorption,  etc.; 
for  ideally  thin  layers,  weighing  and  other  measurement  are 
out  of  the  question. 

I  do  not  think  that  this  latter  objection  ought  to  be  dis- 
missed lightly,  when  we  find  such  a  phenomenon  as  the  al- 
most universal  ionization  of  the  atmosphere  ascribed  to  the 
presence  of  radium  or  its  educts.  Thomson  himself  has  shown 
a  variety  of  ways  for  ionizing  air,  when  any  variation  in  the 
amount  of  radium  present  —  or,  rather,  absent  —  is  out  of 
the  question;  some  of  these  serve  particularly  well  to  explain 
the  phenomena  in  the  open  air.  Recently,  indeed,  quite  a 
number  of  investigators  have  observed  diurnal  variations  in 
this  atmospheric  ionization,  sufficiently  marked  to  require 
some  other  explanation  than  the  production  of  emanations 
from  the  earth  or  surrounding  materials.  Gustave  Le  Bon, 
in  his  "Evolution  de  la  Matiere,"  shows  how  the  gold-leaf 
electroscope  is  discharged  when  connected  with  some  very 
dry  sulphate  of  quinine,  which  is  taking  up  hygroscopic 
moisture.  Are  we  ready,  with  him,  to  assume  that  the  quinine 
is  catalyzing  some  atoms  into  Nirvana,  or  that  the  electro- 
scope may  indicate  many  changes  that  are  not  intra-atomic? 


REPORT  OF  THE  COMMITTEE  OF  THE  OVER- 
SEERS TO  VISIT  THE  CHEMICAL  LABORATORY 
OF  HARVARD  COLLEGE 

To  THE  BOARD  OF  OVERSEERS  OF  HARVARD  COLLEGE:  — 
Your  Committee  beg  leave  to  report  that  they  visited 
the  Chemical  Laboratory  on  Tuesday,  March  9th,  1909, 
and  were  received  by  Professors  Jackson,  Sanger,  Richards, 
Torrey,  and  Baxter,  and  Dr.  Henderson.  At  the  opening  of 
the  meeting  an  expression  of  deep  regret  at  the  recent  death 
of  Dr.  Wolcott  Gibbs,  Professor  Emeritus  and  distinguished 
chemist,  was  recorded.  After  the  reading  of  reports  on  the 
present  condition  of  the  building,  and  some  discussion,  the 
Committee  were  shown  over  the  laboratories. 

The  condition  of  the  laboratories  in  Boylston  Hall  has  been 
so  fully  set  forth  in  previous  reports  that  it  seems  now  hardly 
worth  while  to  repeat  in  full  the  criticisms  as  to  their  condi- 
tion, which  have  been  so  repeatedly  made.  It  may  be,  how- 
ever, of  advantage  on  this  occasion  to  refer  to  one  or  two 
points  of  pressing  importance.  The  needs  of  those  desiring  to 
study  chemistry  at  this  University  may  be  divided  into  two 
classes:  first,  the  needs  of  the  undergraduates,  and,  second, 
the  needs  of  those  conducting  research. 

So  far  as  the  undergraduates  may  be  concerned,  the  most 
pressing  necessity  at  the  present  time  is  for  the  better  accom- 
modation of  students  in  qualitative  analysis.  The  space  as- 
signed to  this  work  has  been  so  inadequate  that  additional 
accommodations  have  been  found  for  the  students  in  the 
west  wing  and  basement  of  Dane  Hall.  For  those  who  are 
working  in  what  is  now  termed  Chemistry  1,  there  is  such 


REPORT  ON  CHEMICAL  LABORATORY    79 

imperfect  accommodation  that  about  half  of  the  students 
have  been  forced  to  carry  on  work  in  the  unsanitary  cel- 
lar, now  called  Room  A.  There  is  no  space  anywhere  for 
laboratory  instruction  in  elementary  organic  or  in  technical 
chemistry. 

Turning  now  to  the  needs  for  research :  For  organic  research 
the  accommodation  is  fair,  but  not  ample  or  comfortable. 
For  inorganic  and  physico-chemical  research  the  facilities 
are  very  bad,  and  for  technical  research  there  are  no  facilities 
at  all,  nor  is  agricultural,  sanitary,  or  biological  chemistry  at 
all  provided  for  in  Cambridge. 

In  precise  investigation  of  atomic  weights,  Harvard  prob- 
ably leads  the  world.  Such  work  demands  well-ventilated 
rooms,  free  from  dust  and  noxious  vapors  of  all  kinds,  —  for 
these  may  ruin  the  purity  of  the  substance  to  which  months 
of  care  have  been  devoted.  Researches  in  physical  chemistry 
need  rooms  of  constant  temperature,  free  from  vibrations 
and  changes  in  electrical  field.  This  work  is  now  so  badly 
provided  for  that  it  is  greatly  hampered. 

The  lecture-rooms,  which  for  the  most  part  were  designed 
at  the  time  of  the  first  occupancy  of  Boylston  Hall  in  1857, 
are  now  not  only  inadequate  for  the  number  of  students  to 
be  accommodated,  but  are  lacking  in  ventilation,  and  are  too 
few  for  the  proper  preparation  of  experimental  lectures. 

One  of  the  most  important  needs  at  the  present  time  is  a 
better  provision  for  the  administration  of  laboratory  and 
storeroom,  —  a  very  important  feature  in  the  economical 
carrying  on  of  a  well-conducted  laboratory. 

When  the  present  building  was  built,  there  were  about  one 
hundred  students  in  the  required  lecture  and  recitation  course, 
but  few  laboratory  students.  The  number  of  the  latter  stead- 
ily increased  from  time  to  time,  and  the  other  departments 
of  the  University  which  also  found  room  in  Boylston  Hall 


80  MORRIS  LOEB 

were  gradually  crowded  out,  until  in  1900  every  nook  and 
corner  in  the  building  which  could  be  utilized  had  been  ex- 
hausted. The  consequence  was  that  when  over  six  hundred 
men  applied  for  desks  that  year  there  was  a  waiting  list  of 
forty  men.  This  continued  for  several  years,  and  the  Univer- 
sity was  in  the  position  of  not  being  able  to  make  good  its 
announcements  concerning  chemistry.  With  this  overcrowd- 
ing, a  steady  deterioration  has  taken  place  in  the  equipment 
of  the  building,  and  the  result  is  that  many  men  are  now  de- 
terred from  taking  the  elementary  course  in  chemistry  on 
account  of  the  known  conditions  of  the  laboratory.  It  is  also 
probable  that  many  students  do  not  go  on  with  advanced 
work  on  account  of  the  unfavorable  conditions  under  which 
they  have  to  work. 

It  has  been  suggested  that  the  present  building  should  be 
entirely  refitted  internally,  but  its  arrangement  at  the  present 
time  is  so  entirely  unadapted  to  alterations  of  any  kind  that  it 
would  be  necessary  to  tear  out  the  whole  interior  of  the  build- 
ing, and  even  then  it  is  not  probable  that  a  satisfactory  ar- 
rangement of  a  new  set  of  laboratories  and  lecture-rooms  on 
a  modern  basis  could  be  planned  within  its  four  walls,  as 
careful  measurements  of  Boylston  Hall  show  that  the  avail- 
able space  within  the  walls  would  not  be  adequate  for  the  needs 
of  the  department  if  the  building  were  to  be  remodeled.  A 
further  use  of  Dane  Hall,  aside  from  the  obvious  inconven- 
ience of  two  separated  buildings,  would  not  give  sufficient 
room  for  expansion.  In  short,  any  remodeling  or  enlarging  of 
present  quarters  would  be  but  a  makeshift.  For  this  reason 
it  was  borne  home  strongly  to  the  members  of  the  Committee 
as  it  has  been  for  a  long  time  to  the  members  of  the  teaching 
staff,  that  these  needs  can  be  met  in  an  adequate  way  only 
by  the  construction  of  a  number  of  new  buildings,  —  the 
separate  buildings  being  devoted  to  different  branches  of 


REPORT  ON  CHEMICAL  LABORATORY    81 

chemistry,  and  placed  not  far  apart,  to  be  connected  with 
each  other  by  a  central  Administration  Building.  The  latter 
might  contain  also  the  chief  lecture-rooms,  a  chemical  museum, 
as  well  as  a  library,  and  other  facilities  to  be  used  in  common 
by  all;  separate  buildings,  as  has  been  stated,  to  be  devoted 
to  the  different  branches  of  chemistry.  One  could  be  devoted 
to  organic  and  industrial  chemistry;  a  second  to  inorganic 
chemistry;  a  third  to  physical  chemistry,  and  a  fourth  to 
quantitative  and  qualitative  analysis.  Portions  of  one  or  more 
of  these  buildings  could  be  set  aside  as  research  laboratories, 
of  their  respective  kinds.  In  this  way  provision  would  advan- 
tageously be  made  for  the  adequate  separation  of  work  in- 
jurious to  other  parts,  either  because  of  noise,  vibration,  or 
noxious  gases;  on  the  other  hand,  connection  with  the  cen- 
tral Administration  Building  would  promote  unity  of  interest. 

Preliminary  sketches  of  several  ways  in  which  these  build- 
ings might  be  arranged  were  shown  to  the  Committee.  Such 
a  scheme  of  a  group  of  buildings  devoted  to  chemistry  would 
necessarily  demand  considerable  space  of  ground,  but  the 
Committee  understand  that  land  for  this  purpose  is  available 
in  Cambridge  in  a  situation  which  would  not  only  be  well 
adapted  to  the  purposes  of  the  buildings  erected  upon  it,  but 
would  enable  them  to  become  an  ornamental  addition  to  the 
various  groups  of  buildings  now  in  the  University  grounds. 

Such  a  proposed  radical  departure  of  the  administration 
of  the  Department  of  Chemistry  would  undoubtedly  involve 
a  large  expenditure,  but  when  we  consider  the  importance  of 
the  subject  and  the  character  of  the  teachers  and  investiga- 
tors who  are  interested  in  this  department  of  science,  we  do 
not  hesitate  to  recommend  most  urgently  that  steps  be 
taken  in  order  that  a  beginning  may  be  made  to  work  out  an 
entirely  new  foundation  for  this  department. 

With  the  immense  development  of  the  various  departments 


82  MORRIS  LOEB 

of  science  which  has  taken  place  since  the  chemical  depart- 
ment was  first  established  on  its  present  basis,  attention  has 
been  so  acutely  drawn  to  other  fields  of  labor  that  the  public 
has  failed  to  grasp  the  important  rdle  which  has  been  played 
by  pure  chemistry  in  almost  all  of  the  departments  of  indus- 
try and  science  which  have  contributed  toward  the  advance- 
ment of  the  material  prosperity  of  mankind.  It  seems  proper, 
therefore,  to  call  attention  at  this  time  to  the  r61e  which 
chemistry  has  played  in  this  great  awakening  of  science  in  its 
application  to  humanity. 

In  the  first  place,  in  this  age  of  steel,  much  depends  upon 
the  chemical  manufacture  of  the  various  kinds  of  hardened 
iron.  As  iron  does  not  occur  in  commercial  quantities  in  a 
native  state,  the  preparation  of  all  the  enormous  quantity 
which  is  used  depends  entirely  upon  making  a  sufficiently 
pure  product  by  a  method  which  avoids  unnecessary  waste. 
Both  the  elaboration  of  the  method  and  the  determination  of 
the  purity  of  the  material  can  be  accomplished  only  by  trained 
chemists;  moreover,  the  protection  of  the  finished  product 
from  the  chemical  change  of  rusting  lies  also  in  the  same  hands. 
When  one  takes  into  consideration  the  fact  that  steel  serves 
not  only  a  chief  role  in  the  construction  of  ships,  bridges, 
and  buildings,  but  also  is  concerned  in  the  manufacture  of 
almost  every  article  which  we  use,  because  of  the  need  of 
steel  tools  of  suitable  quality,  one  can  see  how  great  an  in- 
direct part  chemistry  plays  in  every  act  of  our  life.  Indeed, 
all  the  building  materials  of  the  future,  such  as  the  composi- 
tion of  concrete,  and  the  manufacture  of  glass  and  of  pottery, 
present  at  the  present  time  chemical  problems  of  enormous 
interest. 

Another  great  industry,  the  soda  industry,  is,  of  course, 
wholly  chemical,  and  so  is  the  soap  industry,  which  depends 
upon  it.  Before  chemists  had  shown  the  world  how  alkalies 


REPORT  ON  CHEMICAL  LABORATORY    83 

could  be  made  on  a  large  scale,  these  all  important  sub- 
stances were  to  be  obtained  only  from  the  ashes  of  wood  and  of 
seaweed.  The  consequence  was  that  both  soap  and  glass  were 
very  expensive,  and  the  result  to  the  growth  of  civilization 
was  lamentable.  The  cleanliness,  and  therefore  the  health, 
of  the  world  is  due  to  Leblanc,  and  since  then  to  Solvay,  two 
chemists  who  have  made  soap  cheap  enough  to  replace  the 
mediaeval  perfumes  which  were  made  to  conceal  the  dirt. 

The  two  great  departments  of  applied  biological  chemis- 
try are  medicine  and  agriculture,  and  it  is  only  now  that  sys- 
tematic and  hopeful  attempts  are  being  made  to  apply  chemi- 
cal knowledge  broadly  in  these  fields.  Already  there  can  be 
no  doubt  that  progress  in  this  direction  in  the  next  few 
decades  will  be  enormous.  It  has  been  arrested  during  the 
last  five  or  six  decades  because  pure  chemistry,  after  develop- 
ing for  years  in  connection  with  medicine  and  agriculture, 
found  itself  at  a  point  where  it  had  to  turn  to  a  systematic 
development  of  its  whole  field.  Now,  however,  this  develop- 
ment has  gone  on  so  far  that  much  can  be  done  with  our  pres- 
ent knowledge  of  organic  chemistry  and  physical  chemistry, 
and  much  more  will  be  possible  in  the  future  if  this  develop- 
ment of  pure  chemistry  goes  on  with  the  same  acceleration 
as  in  the  past. 

For  the  welfare  of  the  human  race,  it  is  essential  that  this 
acceleration  should  continue,  and  there  is  no  loftier  public 
service  than  advancing  these  activities.  The  advantageous 
results  of  dealing  scientifically  with  such  subjects  are  to  be 
found  everywhere  in  health  and  comfort,  in  relative  freedom 
from  pain,  in  increased  immunity  to  disease,  so  far  as  medi- 
cine is  concerned;  in  greatly  lessened  labor  and  enormously 
increased  efficiency  of  labor,  resulting  in  wonderful  increase 
of  productivity,  and  general  economic  amelioration  for  scien- 
tific agriculture. 


84  MORRIS  LOEB 

In  the  industries  in  which  fermentation  is  a  problem  to  be 
dealt  with,  individual  chemical  research  plays  an  important 
role,  and  it  was  while  pursuing  such  investigations  that  Pas- 
teur discovered  the  great  r61e  of  bacteria,  revolutionizing  at 
the  same  time  the  whole  domain  of  another  department  of 
science,  —  medicine. 

In  agriculture  we  find  a  striking  example  of  the  value  of 
pure  science,  for  here  it  was  that  the  investigations  and  ex- 
periments of  Liebig  clarified  and  simplified  the  subject. 

The  fertility  of  the  earth  depends  upon  the  chemical  man- 
ures, and  it  is  calculated  that  in  thirty  years  the  present  source 
of  nitrogen  (Chile  saltpetre)  will  be  exhausted.  The  loss  of 
nitrogen  in  combustion,  and  otherwise  in  civilization,  is  a 
permanent  one.  Chemical  means  exist  for  getting  it  back 
from  the  air.  With  power  from  electricity  producing  a  high 
temperature,  we  can  get  nitric  acid  from  the  air,  so  that  the 
danger  of  giving  up  intensive  agriculture  from  lack  of  nitrog- 
enous manure  has  been  averted  by  chemistry. 

The  chief  product  of  farming  is  starch,  which  forms  the 
bulk  of  all  edible  vegetables,  for  that  is  the  chief  food  of 
man,  and  in  a  larger  degree  it  is  the  chief  food  of  the  herb- 
ivorous domestic  animals.  The  amount  of  starch  which  is 
consumed  as  food  by  man  and  the  domestic  animals  in  the 
United  States  alone  cannot  be  far  below  fifty  million  tons 
per  year.  In  addition  to  this  enormous  use  of  the  sub- 
stance, great  quantities  of  it  are  being  converted  into  glu- 
cose and  into  alcohol,  and  the  use  of  starch  for  these 
purposes  as  our  scientific  technology  develops  in  this  di- 
rection, promises  to  be  far  greater  than  at  present.  We 
may,  indeed,  expect  that  glucose  will  largely  replace  cane 
sugar,  and  we  are  now  assured  from  our  present  improved 
devices  that  alcohol  may  be,  at  need,  substituted  for  coal 
and  the  products  of  petroleum  in  the  production  of  heat  and 


REPORT  ON  CHEMICAL  LABORATORY    85 

power.  The  technology,  then,  of  an  inconspicuous  substance, 
if  we  may  use  the  term,  such  as  starch,  becomes  at  once  one 
of  the  greatest  problems  in  the  whole  field  of  economics,  the 
proper  treatment  of  which  depends  upon  the  past  achieve- 
ments in  the  field  of  pure  chemistry  and  progress  to  come  in 
that  field. 

The  development  of  paper  from  wood  pulp  is  now  a  source 
of  great  danger  to  our  forests.  The  question  of  getting 
pulp  from  straw  and  cornstalks  for  this  purpose  becomes, 
therefore,  an  important  one,  in  the  solution  of  which  the 
prosperity  of  the  country  is  intimately  involved. 

The  improvements  of  our  textile  fabrics,  such  as  the  manu- 
facture of  artificial  silk,  have  great  possibilities  for  advance- 
ment. 

All  the  new  processes  for  reproducing  photographic  pic- 
tures are  largely  chemical  problems,  as  are  also  coinage, 
chemical  assaying,  and  the  whole  domain  of  metallurgy. 

Coming  now  to  the  medical  side  of  the  question,  we  see  at 
once  that  the  science  of  nutrition  and  the  value  of  every  dif- 
ferent kind  of  food  in  the  maintenance  of  health,  and  its 
adaptation  to  disease,  are  all  chemical  problems,  which  are 
becoming  topics  of  increasing  interest  to  those  who  are  assist- 
ing actively  in  the  advance  of  practical  medicine.  The  actual 
control  of  the  food  supply  is  largely  chemical,  and  the  pure 
food  laws  can  be  enforced  only  through  chemistry. 

Of  the  many  applications  of  chemistry  to  medicine,  the 
problem  of  immunity  in  its  broadest  sense  is  perhaps  one  of 
the  most  important,  and  then  we  have  also  the  problem  re- 
garding those  diseases  which  are  in  the  largest  sense  sys- 
temic, —  like  diabetes,  gout,  and  some  of  the  atrophies,  and 
even  senility  itself.  It  is  possible  even  that  the  question  of 
the  origin  of  cancer,  one  of  the  few  diseases  which  has  thus  far 
baffled  research,  and  which  so  far  as  we  know  is  probably  not 


86  MORRIS  LOEB 

of  microbic  origin,  may  turn  out  eventually  to  be  a  purely 
chemical  problem. 

The  whole  domain  of  hygiene  and  preventive  or  state 
medicine  is  a  field  of  investigation  which  only  those  well 
trained  in  chemical  research  can  deal  with  intelligently.  A 
chemical  training  is,  therefore,  an  essential  part  of  the  educa- 
tion of  the  health  officer,  who  plays  so  increasingly  important 
a  r61e  in  the  economy  of  our  modern  civilization. 

It  is  hardly  necessary  to  maintain  at  length  here  the  boon 
to  humanity  which  such  chemical  substances  as  ether,  chloro- 
form, and  cocaine  have  been,  and  the  important  role  which 
many  of  the  coal  tar  products  have  played  in  pharma- 
cology. 

The  law  against  arsenic  in  wall-papers  was  the  result  of 
a  movement  which  was  started  from  the  University  Labora- 
tory, being  put  on  a  scientific  basis  by  Professor  Sanger's 
proof  that  arsenical  wall-papers  were  injurious,  by  analyses 
of  the  urine  of  patients.  The  debt  which  surgery  owes  to 
this  University  for  the  part  it  played  in  the  introduction  of 
ether  as  an  anesthetic  in  surgical  operations  should  not  be 
forgotten. 

The  structure  of  many  physiologically  active  substances 
has  now  been  made  out,  and  by  making  allied  substances 
with  similar  structure,  by  an  experimental  transposition  of 
molecules  in  the  hands  of  trained  workers,  many  new  and 
equally  valuable  drugs  may  be  obtained.  This  scientific 
search  for  medicine,  which  is  still  in  its  infancy,  is  sure  of 
bringing  great  results  in  the  future. 

Finally,  from  a  purely  business  point  of  view,  the  encourage- 
ment of  chemical  research  is  of  the  highest  importance.  As 
competition  increases,  the  successful  man  will  more  and  more 
be  the  one  who  lets  nothing  go  to  waste,  but  adopts  the  most 
efficient  processes  and  devises  new  ones  still  more  efficient; 


REPORT  ON  CHEMICAL  LABORATORY    87 

who  works  up  his  by-products  into  some  useful,  and,  there- 
fore, valuable  substances,  who  economizes  energy,  whether 
k  this  energy  comes  from  coal  or  water  power,  or  human  labor. 
The  field  is  too  large  and  chemical  laws  too  complex  to  have 
the  results  come  accidentally.  They  can  be  accomplished  only 
by  a  systematic  investigation  of  the  whole  field  of  chemistry. 
Only  upon  the  study  of  pure  chemistry  and  the  laws  which 
underlie  it,  can  be  built  the  practice  of  chemical  technology, 
just  as  our  whole  modern  technique  of  electricity  was  built 
upon  the  purely  scientific  experiments  of  Faraday,  or  the 
modern  system  of  wireless  telegraphy  was  built  upon  the  cal- 
culations of  Clerk  Maxwell,  and  the  scientific  experiments  of 
Hertz.  An  improvement  of  a  chemical  process  which  betters 
the  yield  by  five  per  cent  may  mean  $10,000,000  a  year  to  a 
single  large  corporation  in  a  time  not  far  distant,  if  not  even 
to-day.1  Colossal  fortunes  have  already  been  made  in  this 
way.  It  is  slowly  creeping  into  the  minds  of  business  men 
and  manufacturers,  that  a  trained  chemist  can  improve  an 
output  or  effect  economies,  and  that  something  more  than 
a  mere  analyst  is  necessary  in  a  manufacturing  concern.  But 
how  many  persons  understand  that  chemistry  is  essential 
in  most  plans  for  the  social  uplifting  of  the  people? 

In  Europe  it  is  a  truism  that  well-endowed  and  active 
laboratories  of  pure  chemistry  are  a  source  of  wealth  to  the 
community,  and  nothing  is  more  striking  than  the  close  co- 
operation between  the  German  chemical  professors  and  the 
"works-chemists"  of  the  great  German  chemical  industries. 
This  cooperation  it  is  which  has  put  the  German  chemical 
industry  at  the  head,  with  no  other  country  a  respectable 
second.  England  is  fast  losing  her  supremacy  in  manufac- 
turing where  chemistry  plays  a  part,  and  the  success  of  the 

1  The  gross  income  of  the  Steel  Corporation  in  1907  was  $757,000,000;  its  net 
income  available  for  sinking  funds,  interest,  dividends,  etc.,  was  $160,000,000. 


88  MORRIS  LOEB 

Germans  and  the  backwardness  of  the  English  is  to  be  at- 
tributed to  the  difference  of  the  educational  systems  of  the 
two  countries,  in  the  large  supply  of  highly  educated  chemists 
in  Germany,  and  the  smaller  supply  and  want  of  their  employ- 
ment in  England.  In  a  very  large  degree,  the  commercial 
prosperity  of  the  German  Empire  is  dependent  upon  this 
supremacy.  The  German  Emperor  himself  has  said  this,  and 
it  is  generally  believed  in  German  universities.  The  Badische 
Anilin  und  Soda  Fabrik  employs  more  than  one  hundred 
men  on  pure  research,  and  other  corporations  in  proportion, 
not  only  for  purely  chemical  work,  but  for  the  manufacture 
of  iron  and  steel,  and  in  other  kinds  of  industry. 

There  are  two  chemical  plants  in  Germany,  each  as  big  as 
the  General  Electric  Company's  plant,  whose  works  are  so 
correlated  that  the  waste  products  of  one  serve  as  the  valu- 
able products  for  the  other.  From  one  to  two  hundred  doc- 
tors of  philosophy  in  chemistry  are  employed  in  some  of  these 
great  establishments. 

The  importance  of  chemistry  on  the  continent  of  Europe 
is  attested  in  a  remarkable  manner  by  the  expenditures  of 
the  several  governments  for  the  equipment  and  mainte- 
nance of  the  chemical  laboratories  of  their  universities  and 
schools  of  technology.  In  Berlin,  for  example,  the  cost  of  a 
laboratory  built  about  twelve  years  ago  for  Fischer,  was 
1,316,000  marks,  with  64,000  marks  more  for  a  connected 
dwelling-house  for  the  director.  There  are  in  Berlin,  in  ad- 
dition to  this  laboratory,  laboratories  of  inorganic  chemistry 
and  of  physical  chemistry  for  the  university,  and  a  fine  large 
chemical  laboratory  for  the  technical  school.  All  these  labora- 
tories together  probably  cost  a  good  deal  more  than  3,000,000 
marks. 

Strassburg  is  a  university  with  about  one  third  as  many 
teachers  and  students  of  chemistry  as  Harvard.  The  Strass- 


REPORT  ON  CHEMICAL  LABORATORY    89 

burg  laboratory  is  devoted  to  organic  and  inorganic  chemistry 
exclusively.  To  build  it  to-day  in  Cambridge  would  cost 
about  $300,000.  Allowing  for  difference  in  cost  of  construc- 
tion, either  of  these  cases  indicates  that  the  Prussian  govern- 
ment would,  in  a  case  like  Harvard's,  devote  about  $1,000,- 
000  to  the  construction  of  chemical  laboratories. 

Not  less  significant  are  the  yearly  budgets  of  some  of  the 
European  universities.  In  Berlin  the  chemical  laboratory 
above  mentioned  has  from  the  government  80,000  marks  a 
year  for  running  expenses,  the  physico-chemical  laboratory 
20,000  marks.  These  sums  are  in  no  part  derived  from  tui- 
tion fees,  but  are  direct  subsidies.  Together  with  the  similar 
appropriations  for  the  other  chemical  laboratories  of  the  uni- 
versity and  the  technical  school  they  certainly  exceed  150,000 
marks  yearly.1 

In  Berlin  the  physical  laboratory  receives  33,000  marks  a 
year.  The  university  library  has  121,000  marks,  which  is  not 
more  than  three  fourths  the  sum  devoted  to  all  the  chemical 
laboratories  of  the  university  and  the  technical  school,  and 
only  fifty  per  cent  more  than  the  sum  devoted  to  one  of 
them. 

In  Leipsic  the  three  chemical  laboratories  have  80,000 
marks  a  year  for  running  expenses,  the  physical  laboratory 
only  about  27,000  marks. 

In  Strassburg  the  chemical  laboratory  has  34,000  marks 
a  year,  the  physical  laboratory  14,000  marks;  the  library, 
which  serves  both  university  and  province  (Alsace-Lorraine), 
has  about  72,000  marks.  If  one  assigns  one  half  of  this  library 
budget  to  the  university  and  one  half  to  the  province,  it  ap- 
pears that  a  chemical  laboratory  which  is  dealing  with  only 
two  of  the  important  divisions  of  chemistry  and  has  but  one 

1  The  Harvard  laboratory  has  from  the  Corporation  approximately  $900  yearly 
for  running  expenses.  Other  sources  of  income  are  similar  in  the  two  countries. 


90  MORRIS  LOEB 

professor  ordinarius,  and  but  one  professor  extraordinarius, 
receives  nearly  as  much  money  as  the  university  library  for 
running  expenses. 

In  Zurich  the  university  chemical  laboratory  is  voted 
f .24,800  a  year.  This  sum  is  approximately  equal  to  the  total 
yearly  appropriations  for  the  laboratories  of  physics,  bot- 
any, zoology,  anatomy,  physiology,  and  pathology  together 
(f. 25,600). 

These  facts  indicate  that  a  German  or  Swiss  government 
would,  in  a  case  like  Harvard's,  devote  about  $25,000  a  year 
to  the  maintenance  of  chemical  laboratories.  These  data, 
together  with  the  confirmatory  facts,  also  indicate  that  in 
Germany  and  Switzerland  the  chemical  laboratories  are  re- 
garded as  of  equal  importance  with  the  university  library, 
about  three  times  as  important  as  physical  laboratories,  and 
as  equalling  in  importance  the  institutes  of  six  other  sciences 
taken  together. 

Speakers  at  meetings  in  America  which  have  any  bearing 
on  chemistry  intimate  that  we  are  beginning  to  profit  by 
this  lesson,  and  are  using  trained  scientific  knowledge  in  ever 
increasing  proportion,  and  that  the  results  can  be  already 
seen. 

The  General  Electric  Company  employs  from  twenty  to 
twenty-five  physicists  and  chemists,  and  the  Eastman  Kodak 
Company,  which  is  highly  successful,  employs  three  or  four 
research  chemists.  The  Pennsylvania  Railroad  has  a  large 
staff  of  chemists  assisting  their  research  chemist  in  studying 
the  qualities  of  steel. 

If  we  admit  as  a  principle  that  the  funds  should  be  distrib- 
uted to  each  department  of  the  University  in  due  proportion, 
then  we  think  that  the  claims  of  the  Department  of  Chemistry 
should  stand  very  high.  Harvard  has  always  been  a  leader 
in  university  education  in  this  country,  and  it  is  still  aiming 


REPORT  ON  CHEMICAL  LABORATORY    91 

strenuously  to  maintain  that  position.  Is  it  not  wise,  there- 
fore, in  planning  the  education  of  her  students,  to  give  due 
encouragement  to  the  distinguished  staff  which  is  now  labor- 
ing under  exceeding  difficulties  to  maintain  a  well-earned 
supremacy  in  this  department? 

Is  it  not  advisable  that  Harvard  should  recognize  the  new 
movement  of  industrial  chemistry?  Should  she  not  be  a  leader 
in  this  line  of  research,  and  come  thus  in  close  touch  with  the 
wants  of  the  people  by  showing  them  how  to  make  produc- 
tion more  effective?  By  following  the  policy  already  adopted 
by  some  of  the  state  universities  and  giving  instruction  in 
agricultural  chemistry,  it  is  not  too  wild  a  dream  to  hope  that 
the  abandoned  farms  of  New  England  may  be  blossoming 
like  gardens  in  the  next  fifty  years. 

Your  Committee  do  not,  therefore,  hesitate  to  indorse  the 
plan  already  outlined  by  this  department.  It  is  estimated 
that  buildings  of  the  character  contemplated  can  be  built  for 
$500,000;  a  further  sum  of  $500,000  would  be  needed  for  the 
proper  endowment  of  such  a  plan.  This  is  in  itself  doubtless 
a  large  sum,  but  small  in  comparison  with  amounts  expended 
on  many  industrial  projects. 

Although  it  may  not  be  possible  to  carry  out  this  scheme 
at  once  on  the  scale  contemplated,  the  establishment  of  a  re- 
search laboratory  as  a  beginning  would  be  of  great  benefit, 
if  the  project  could  be  carried  out  on  a  consistent  plan, 
which  should  be  adopted  at  the  outset.  The  estimates  for 
such  a  laboratory  have  been  made,  and  in  round  numbers 
would  amount  to  about  $50,000  for  building  and  installa- 
tion. A  further  sum  of  $50,000  would  be  needed  for  en- 
dowment. 

The  Committee  would,  therefore,  urge  strongly  that  an 
attempt  be  made  at  once  to  obtain  $100,000  for  this  pur- 
pose, and  thus  make  a  beginning  of  the  development  of  this 


92  MORRIS  LOEB 

department  on  a  scale  suited  to  its  needs  at  the  present 
time.1 

The  last  century  has  been  a  century  of  mechanical  power, 
made  available  by  the  perfection  of  machinery  and  the 
development  of  electricity.  The  coming  century  promises  to 
be  a  chemical  century.  Should  Harvard,  if  all  this  be  true, 
be  content  until  it  has  obtained  the  best  chemical  laboratory 
in  the  world? 

J.  COLLINS  WARREN, 
CLIFFORD  RICHARDSON, 
JAMES  M.  CRAFTS, 
MORRIS  LOEB. 

March  27,  1909. 

1  Within  a  month  from  the  date  of  this  report  Professor  Loeb  and  his  brother 
James  Loeb  generously  carried  out  the  Committee's  recommendation  by  offering 
$50,000  for  the  proposed  building,  provided  that  other  friends  of  the  University 
should  subscribe  an  equal  sum.  The  project  is  now  completed,  and  the  research 
laboratory,  named  the  Wolcott  Gibbs  Memorial  Laboratory  through  the  suggestion 
of  Dr.  Loeb,  is  now  in  full  operation.  [Editor,  April,  1913.] 


THE  CONDITIONS  AFFECTING  CHEMISTRY 
IN  NEW  YORK1 

IN  assuming  the  chair,  I  am  confident  that  the  coming 
year  will  be  one  of  great  progress  in  our  section's  history, 
not  through  any  merit  of  its  officers,  but  through  the  ever- 
increasing  spirit  of  cooperation  among  the  members,  and  the 
rapid  strides  which  research  and  industry  are  making  in  this 
country.  You  will  hear  reports,  this  evening,  of  two  im- 
portant general  meetings  of  interest  to  our  membership, 
that  of  our  own  society  at  Detroit  and  that  of  the  Interna- 
tional Congress  of  Applied  Chemistry  at  London.  In  both, 
members  of  this  section  bore  a  worthy  share,  and  it  is  a  grati- 
fying tribute  to  American  progress  in  science  and  industry, 
that  the  International  Congress  chose  America  for  its  next 
meeting-place.  It  is  not  only  the  foreigner  who  lands  at 
Ellis  Island  that  deems  America  synonymous  with  New 
York,  and  the  members  of  this  section  must  be  prepared  to 
do  their  full  duty,  during  the  next  three  years,  in  order  that 
our  foreign  brethren  may  carry  back  from  their  visit  a  crys- 
talline rather  than  a  colloidal  vision  of  chemistry  in  America. 

And  so,  gentlemen,  I  have  preferred  to  devote  the  minutes 
which  custom  permits  your  chairman  to  employ  in  airing  his 
personal  views,  to  a  survey  of  the  conditions  affecting  chem- 
istry in  New  York,  rather  than  to  the  presentation  of  some 
debatable  scientific  ideas,  as  I  had  originally  intended.  The 
choice  of  the  more  subjective  topic  is  rendered  more  appro- 
priate by  the  fact  that  this  meeting  is  to  be  followed  by  a 

1  Address  of  the  chairman  of  the  New  York  Section  of  the  American  Chemical 
Society,  delivered  October  8,  1909.  Reprinted  from  Science,  N.  S.,  30,  No.  776, 
pp.  664-£8,  November  12,  1909. 


94  MORRIS  LOEB 

session  of  The  Chemists'  Club,  called  for  the  purpose  of 
settling  a  question  vitally  affecting  the  interests  of  New 
York  chemists. 

Eighteen  years  ago,  when  the  men  who  had  carried  the 
American  Chemical  Society  through  so  many  vicissitudes 
organized  this  section,  in  order  that  the  general  society 
might  become  a  truly  national  one,  I  had  the  honor,  rather 
than  the  duty,  of  being  the  first  local  secretary.  The  meetings 
were  so  poorly  attended,  the  original  papers  so  scarce,  and 
the  general  business  so  unimportant,  that  no  heavy  work 
devolved  upon  its  officers.  We  met  in  the  chapel  of  the  old 
university  building,  where  Professor  Hall  and  I  had  our  primi- 
tive laboratories,  out  of  which  we  carved,  with  some  difficulty, 
shelf -room  for  the  fragmentary  society  library.  When  we  felt 
in  need  of  a  little  variety,  we  sat  in  Professor  Chandler's 
lecture-room  in  49th  Street  and  listened  to  the  passing  trains; 
or  in  East  23d  Street,  peered  at  the  chairman  ensconced 
behind  batteries  of  Professor  Doremus's  bell-jars  and  air- 
pumps.  An  attendance  of  forty  members,  I  believe,  was  a 
record-breaking  event. 

I  need  hardly  expatiate  upon  the  wonderful  changes  that 
have  been  wrought  since  1891.  Our  three  colleges  have  moved 
far  uptown,  and  the  splendid  Havemeyer  laboratories  of 
Columbia  and  New  York  University,  and  the  beautiful  new 
chemistry  building  on  St.  Nicholas  Terrace,  make  us  glad 
to  miss  the  dingy  and  crowded  places  where  chemistry  was 
taught  an  academic  generation  ago.  Our  own  section  and 
kindred  societies  have  been  meeting  in  this  hall  of  The  Chem- 
ists' Club  for  the  past  ten  seasons,  and  no  one  can  estimate 
what  share  a  fixed  and  commodious  meeting-place  has  borne 
in  the  marvelous  increase  in  membership  and  attendance. 
The  other  important  factor  is,  of  course,  the  growth  of  chem- 
ical industry  in  this  vicinity. 


CHEMISTRY  IN  NEW  YORK  95 

While  we  can,  therefore,  congratulate  ourselves  upon  the 
great  strides  that  have  been  made,  during  the  past  two  dec- 
ades, it  behooves  us  to  inquire  whether  there  are  not  still 
some  drawbacks  to  our  progress,  not  by  way  of  carping  criti- 
cism, but  for  the  purpose  of  seeking  such  effective  remedies 
that  future  progress  may  be  made  absolutely  certain. 

For  obvious  reasons,  we  need  not  ask  whether  the  internal 
conditions  in  the  chemical  factories  are  satisfactory;  since 
there  the  managers  must  know  that  their  success  depends 
upon  the  scientific  abilities  of  their  chemists.  It  is  doubtful 
whether  the  same  can  be  said  of  the  establishments  which 
employ  a  chemist  or  two  to  apply  specific  tests;  and  it  is  cer- 
tain that  there  are  still  many  factories  which  conduct,  by 
rule  of  thumb,  operations  that  should  be  continually  con- 
trolled by  scientific  tests,  if  shameful  waste  is  to  be  avoided. 

The  American  people  are  but  slowly  learning  the  importance 
of  the  educated  banker  and  the  expert  accountant  alongside 
the  brilliant  financier  and  the  bold  speculator;  similarly, 
while  they  acclaim  the  clever  inventor  and  the  skillful  engineer, 
they  have  yet  to  recognize  the  worth  of  that  expert  account- 
ant of  material  economy,  the  industrial  chemist.  Quite  aside, 
therefore,  from  any  wish  for  greater  profits  to  our  associates 
who  are  gaining  their  daily  bread  as  commercial  or  analytical 
chemists,  patriotic  motives  lead  us  to  the  earnest  hope  that 
closer  watch  upon  the  economy  of  production  may  bring 
about  that  conservation  of  natural  resources  of  which  the 
politicians  prate,  but  for  which  the  chemist  works.  How,  then, 
can  the  status  of  the  independent  commercial  chemist  be 
raised  in  our  city?  By  giving  him  a  central  rally-point;  a 
home  that  proves  to  the  layman  that  his  is  a  skilled  profes- 
sion, not  a  mere  job-hunting  trade;  a  place  where  the  manu- 
facturer or  merchant  can  find  the  man  he  wants  without  a 
rambling  search  through  the  city  directory.  Doubtless,  some 


96  MORRIS  LOEB 

of  our  colleagues  are  so  well  known,  that  all  the  business  comes 
to  them  which  they  can  handle.  But  the  many  additional 
independent  chemists,  whom  our  commercial  situation  de- 
mands, can  only  establish  themselves  if  they  can  secure  proper 
laboratory  facilities,  without  hiring  attics  in  tumble-down 
rookeries. 

Every  year  scores  of  New  Yorkers  graduate  in  chemistry 
from  our  local  institutions  and  return  from  years  of  protracted 
study  in  other  American  and  European  institutions.  They  are 
enthusiastic  for  research;  in  completing  their  theses  they  have 
laid  aside  definite  ideas  for  subsequent  experimentation; 
but  they  have  no  laboratory.  While  waiting  to  hear  from  the 
teachers'  agency  where  they  have  registered,  while  carrying 
on  desultory  correspondence  with  manufacturers  who  may 
give  them  a  chance,  they  do  not  venture  upon  expenditure 
of  time  and  money  to  fit  out  a  private  laboratory,  which  they 
may  be  called  upon  to  quit  any  minute  upon  the  appearance 
of  that  desired  appointment.  Often  necessity  or  tedium  will 
cause  them  to  accept  temporary  work  of  an  entirely  different 
character  and  indefinitely  postpone  the  execution  of  the  ex- 
periments which  they  had  mapped  out.  Who  will  estimate 
the  loss  of  scientific  momentum,  the  economic  and  intellec- 
tual waste,  which  this  lack  of  laboratory  facilities  for  the 
graduate  inflicts  upon  New  York,  as  compared  with  Berlin, 
Vienna,  Paris,  and  London?  Either  our  universities  and 
colleges,  or  private  enterprise,  should  provide  temporary 
desk-room  for  the  independent  research  chemist. 

So  much  for  the  purely  practical  side  of  our  question. 
How  about  the  opportunities  for  presenting  the  results  of 
investigation?  We  all  appreciate  the  excellence  of  the  three 
chemical  journals  published  by  our  own  society,  as  well  as 
that  of  the  Society  of  Chemical  Industry,  and  we  may  say 
that  these,  together  with  the  independently  conducted  peri- 


CHEMISTRY  IN  NEW  YORK  97 

odicals,  enable  everybody  to  obtain  a  hearing;  but  it  does 
seem  to  me  that  the  cost  of  subscribing  to  all  of  these  journals 
is  excessive,  and  that  much  unnecessary  expense  is  incurred 
through  duplication  of  administrative  efforts,  as  well  as 
through  duplication  of  abstracts,  etc.  This,  of  course,  is  a 
problem  with  which  we,  as  a  local  section,  are  not  directly 
called  upon  to  deal;  nevertheless,  it  is  proper  to  call  the  at- 
tention of  those  who  are  interested  in  the  management  of 
chemical  societies  in  America  to  the  fact  that  membership 
alone  in  the  various  chemical  organizations  of  New  York  costs 
upwards  of  fifty  dollars  per  year,  and  that  it  would  be  but 
fair  to  so  arrange  matters  that  the  total  cost  would  be  re- 
duced by  a  sort  of  clubbing  arrangement,  proportionately 
to  the  number  of  societies  to  which  a  member  belongs.  It 
seems  to  me,  however,  that  in  one  particular  point  we  are  at 
a  distinct  disadvantage  as  compared  with  the  foreign  chem- 
ists: the  frequency  of  regular  meetings  at  which  papers  can 
be  presented  for  the  purpose  of  securing  priority  of  publica- 
tion. Would  it  not  be  possible  for  our  various  local  sections, 
including  the  Chemical  Section  of  the  New  York  Academy 
of  Sciences,  to  arrange  the  dates  of  their  meetings  conjointly 
in  such  a  way  that  a  meeting  would  occur  once  a  week  during 
nine  months,  and  once  a  month  during  the  summer,  thus  se- 
curing for  the  New  York  chemist  the  same  opportunities  for 
the  early  presentation  of  a  scientific  discovery  that  are  pos- 
sessed by  his  brethren  in  European  centres?  There  is,  of 
course,  another  remedy  which  appeals  to  me,  though  I  do  not 
express  it  with  any  degree  of  urgency;  namely,  the  consolida- 
tion of  all  local  sections  into  a  single  organization  which  would 
affiliate  its  members  automatically  with  all  the  national  bodies 
now  in  existence,  and  would  turn  over  the  scientific  material 
of  its  meetings  to  those  journals  for  which  it  seemed  most 
suited.  As  a  matter  of  fact,  glancing  over  the  annual  lists  of 


98  MORRIS  LOEB 

our  various  local  organizations,  I  find  a  remarkable  inter- 
changeability  of  officers,  and  can  hardly  imagine  that  the 
interests  of  their  memberships  can  be  very  far  apart  if  the 
chairman  of  the  New  York  Section  of  the  American  Chemical 
Society  in  one  year  is  the  next  year  expected  to  guide  the  for- 
tunes of  the  New  York  Section  of  the  American  Electro- 
chemical Society  or  of  the  Society  of  Chemical  Industry.  If 
this  were  done  and  we  could  then  exert  our  influence  upon 
the  various  general  societies  to  avoid  duplication  of  work, 
by  issuing  their  chemical  abstracts  jointly,  the  strain  on  the 
purses  as  well  as  the  shelves  of  American  chemists  would  be 
greatly  relieved. 

There  is  still  another  point,  however,  in  which  the  Ameri- 
can chemist  is  at  a  great  disadvantage  as  compared  with  the 
European:  the  ease  of  securing  material  for  his  research  and 
of  comparing  his  results  with  those  of  others.  In  Europe, 
especially  in  Germany,  research  is  never  seriously  delayed 
by  lack  of  a  needed  preparation,  whereas  none  of  our  supply 
houses  carry  a  full  stock  of  chemicals.  To  obtain  a  single 
gram  of  some  particular  substance,  needed  for  a  few  pre- 
liminary tests,  frequently  causes  weeks  of  delay,  as  well  as 
the  disproportionate  custom  house  and  brokerage  expenses 
involved  in  the  importation  of  small  quantities.  Besides, 
owing  to  the  better  centralization  of  scientific  laboratories 
in  Europe,  and  the  existence  in  each  case  of  a  fairly  complete 
set  of  specimens  accumulated  in  the  researches  of  large  num- 
bers of  academic  investigators,  it  is  comparatively  easy  to 
obtain  by  correspondence  research  material  or  typical  speci- 
mens for  comparison.  In  this  country,  on  the  other  hand,  lab- 
oratories are  scattered  throughout  the  numerous  colleges 
and  universities,  and  there  are  no  established  rules  by  which 
specimens  must  be  deposited  with  the  laboratory.  In  smaller 
laboratories,  especially,  the  chances  of  preservation  after  the 


CHEMISTRY  IN  NEW  YORK  99 

departure  of  the  investigator  are  not  very  good.  It  would  be, 
consequently,  very  much  more  difficult  to  obtain  such  speci- 
mens here.  I  would  suggest,  therefore,  that  a  chemical  mu- 
seum be  established  in  New  York,  to  perform  for  the  Amer- 
ican chemists  the  functions  that  the  Smithsonian  Institution 
so  admirably  carries  on  for  the  benefit  of  American  naturalists. 
This  museum  would  not  attempt  to  be  a  popular  show-place, 
but  would  embody,  in  the  first  place,  as  complete  a  collec- 
tion as  possible  of  chemically  pure  materials  of  the  rarer  kinds, 
so  as  to  supplement,  but  not  in  any  manner  compete  with, 
the  stock  of  commercial  supply-houses.  Any  scientific  in- 
vestigator would  be  entitled  to  borrow  or  purchase  mate- 
rial required  for  immediate  experimentation,  and  all  used 
articles  would  be  replaced  as  quickly  as  possible.1 

In  the  second  place,  it  would  be  the  depository  for  speci- 
mens of  new  substances  obtained  in  American  research. 
Every  chemist  would  be  invited  to  send  to  the  museum  a 
small  quantity  of  each  substance  newly  prepared  by  him,  not, 
indeed,  as  an  evidence  of  the  good  faith  of  his  investigation, 
but,  rather,  to  enable  future  workers  to  obtain  such  material, 
either  for  comparison,  or  for  further  experimentation  with 
the  least  possible  delay.  Many  substances  that  are  now  car- 
ried away  from  universities  by  students  who  subsequently 
abandon  chemical  research,  or  which  belong  to  the  families 
of  deceased  chemists  who  do  not  know  what  to  do  with  them, 
would  thereby  be  rescued  from  oblivion,  and  might  ultimately 
become  of  the  greatest  value  for  a  special  purpose. 

Thirdly,  this  museum  would  invite  chemical  manufacturers 
to  send  standard  samples  of  their  products,  and  thereby  facili- 
tate the  commercial  relations  between  consumer  and  manu- 
facturer. 

To  such  a  museum  there  could  be  attached  a  competent 

1  A  museum  of  this  kind  was  provided  for  in  Dr.  Loeb's  will.     [EDITOR.] 


100  MORRIS  LOEB 

staff  of  workers  for  the  preparation  of  samples  not  other- 
wise available.  In  the  analysis  of  samples  submitted  as  offi- 
cial standards,  we  should  have  the  beginning  of  that  Che- 
mische  Reichsanstalt  which  is  now  the  chief  object  to  which 
German  chemists  are  directing  their  attention. 

The  past  twenty  years  have  seen  the  construction  of  in- 
numerable teaching  laboratories  in  our  vicinity.  They  have 
seen  an  undreamt-of  development  and  growth  of  chemical 
industry,  and,  above  all,  they  have  seen  the  coming  together 
of  the  scattered  chemists  into  a  large  and  powerful  society. 
Now  is  the  time  when  we  should  make  every  effort  to  direct 
these  forces  that  we  have  marshaled  toward  the  attainment 
of  definite  objects,  and  coordinate  all  our  enterprises  in  those 
directions  that  will  make  for  the  improvement  of  the  intel- 
lectual as  well  as  the  material  conditions  of  our  beloved  city. 


SIR  ISAAC  NEWTON1 

WE  celebrate  so  frequently  the  heroic  deeds  of  warriors 
that  it  may  be  a  welcome  change  to  spend  a  short  hour  in  the 
consideration  of  a  great  man  whose  renown  depends  entirely 
upon  peaceful  victories.  Isaac  Newton  was  a  farmer's  son, 
who  lived  a  quiet  life  of  eighty-five  years  almost  entirely  unaf- 
fected by  the  events  of  the  world  about  him,  but  who  left, 
nevertheless,  monuments  as  important  as  those  which  com- 
memorate any  victory  on  land  or  sea.  He  fought  and  con- 
quered ignorance  and  error;  he  established  new  laws  of 
thought;  he  discovered  for  us  new  beauties  in  nature;  and  he 
opened  before  our  eyes  the  harmonies  of  light  that  are  as 
wonderful  and  as  elevating  as  the  harmonies  of  music.  Un- 
selfish and  regardless  of  worldly  gain,  he  succeeded  in  add- 
ing untold  wealth  and  comfort  to  our  common  store.  Mathe- 
matics, astronomy,  navigation  and  mechanics  all  owe  a  mighty 
debt  to  this  quiet  student;  and  in  Westminster  Abbey  his 
monument  is  well  placed  among  England's  hereos  of  thought 
and  action. 

Sir  Isaac  Newton's  name  means  something  to  every  one 
of  us;  but  I  doubt  whether  the  majority  of  this  audience 
would  be  able  to  indicate  exactly  his  claims  to  fame,  and  you 
may  be  glad  to  have  some  of  them  pointed  out. 

He  was  born  at  Woolsthorpe,  in  Lincolnshire,  on  Decem- 
ber 26,  1642,  — the  year  of  Galileo's  death.  His  father,  Isaac, 
he  never  knew,  and  he  was  brought  up  by  his  mother,  Han- 
nah Ayscough,  and  her  brother.  He  was  educated  at  Gran- 

1  There  is  no  clue  on  the  manuscript  as  to  where  this  lecture  was  delivered.  It 
was  evidently  intended  for  a  popular  audience  having  little  knowledge  of  science. 
Marginal  notes  show  that  it  was  illustrated  by  experiments  and  lantern  slides. 

[EDITOR.] 


102  MORRIS  LOEB 

tham  Grammar  School,  and  in  1657  he  returned  to  his 
mother's  farm;  but  he  cannot  have  been  a  very  successful 
farmer,  since  he  was  described  as  a  very  dreamy  boy,  and  al- 
ways prone  to  study.  Four  years  afterwards,  by  his  uncle's 
advice,  he  entered  Trinity  College,  Cambridge,  and  very  soon 
made  his  mark  as  a  mathematician.  It  was  just  at  this  time 
that  a  great  advance  inaugurated  by  Descartes,  the  applica- 
tion of  algebra  to  geometrical  calculations,  was  arousing  the 
interest  of  mathematicians.  Stimulated  by  this,  young  New- 
ton developed  a  still  grander  advance  by  the  discovery  of  the 
method  of  infinitesimals. 

His  study  at  Trinity  College  was  interrupted  in  1665  by  the 
appearance  of  the  plague  in  Cambridge,  and  he  took  refuge 
at  Woolsthorpe.  A  somewhat  doubtful  but  well  known 
legend  reports  that  here,  in  the  summer  of  1666,  while  he  was 
lying  under  an  appletree  and  ruminating  upon  some  mathe- 
matical question,  a  falling  apple  drew  his  attention  to  those 
phenomena  which  he  later  elucidated  through  his  law  of 
gravitation. 

In  1667  he  returned  to  Cambridge  as  one  of  the  governing 
board  of  his  college,  and  two  years  later,  at  the  age  of  twenty- 
six,  he  became  Lucasian  Professor  of  Mathematics,  and  lec- 
tured chiefly  on  optics,  in  which  branch  of  physics  he  made 
some  of  his  most  remarkable  discoveries.  From  that  time 
on  his  life  was  a  continuation  of  successes.  In  1672  he  was 
elected  to  the  newly  founded  Royal  Society,  practically  the 
oldest  society  for  scientific  research  in  the  world,  of  which  he 
became  President  in  1703.  In  1687  he  published  his  magnum 
opus,  entitled  "  Philosophise  Naturalis  Principia  Mathemat- 
ical He  was  elected  to  Parliament  in  1689,  and  served  for 
many  years.  In  1694  he  was  appointed  Warden  of  the  Mint, 
and  in  1697  Master  of  the  Mint;  and  since  his  time  it  has 
been  the  custom  to  entrust  the  British  Mint  to  some  master  of 


SIR  ISAAC  NEWTON  103 

physical  science.  As  a  result  I  believe  that  the  London  Mint 
has  always  been  foremost  in  the  application  of  scientific  pro- 
cesses to  the  problem  of  securing  permanent  and  stable  coin 
for  the  realm. 

In  1705  Isaac  Newton  was  knighted  by  Queen  Anne,  and 
in  1727,  on  March  20,  laden  with  all  the  honors  which  his 
country  could  bestow  upon  him,  he  died  peacefully,  mourned 
by  all,  hated  by  none.  He  was  buried  with  all  honors  in  West- 
minster Abbey,  and  a  fitting  monument  was  erected  over 
his  grave. 

His  character  is  said  to  have  been  of  the  kindliest,  and  all 
contemporaneous  records  speak  of  his  amiability.  A  patient 
student,  a  keen  observer  of  nature,  and  a  brilliant  inventor, 
he  stands  out  through  his  work  as  one  of  the  greatest  scien- 
tific men  of  all  time.  His  great  services  to  mankind  embraced 
discoveries  in  mathematics,  astronomy,  and  physics.  Perhaps 
his  mathematical  work  ought  to  be  considered  the  most  im- 
portant, for  it  might  be  considered  to  be  at  the  root  of  all  our 
scientific  knowledge,  and  yet  I  despair  of  explaining  to  you 
in  what  these  mathematical  discoveries  consisted.  Up  to 
his  time  it  was  only  possible  to  calculate  with  quantities  that 
were  not  supposed  to  change  during  the  calculations.  He 
showed  us  how  to  work  with  quantities  that  varied.  Before 
him  it  was  necessary  to  imagine  bodies  to  be  at  rest  before 
their  relations  could  be  ascertained;  he  showed  how  to  deal 
with  moving  bodies.  His  invention  "  Fluxions"  (now  called 
the  "  Differential  Calculus")  was  for  the  mathematician  what 
the  Rontgen  discovery  is  for  the  physician.  The  fact  that 
Leibnitz  almost  at  the  same  time  independently  made  the 
same  discovery,  does  not  detract  from  Newton's  merit. 

Having  devised  this  great  improvement  in  calculating  he 
began  to  see  clearly  things  that  Copernicus,  Kepler,  and 
Galileo  had  vainly  attempted  to  comprehend.  Perhaps  the 


104  MORRIS  LOEB 

earlier  investigators  had  actually  understood  these  things 
in  part,  but  not  clearly  enough  to  explain  them  to  others. 
For  example,  there  were  several  ideas  of  Galileo's  about  mo- 
tion which  Newton  has  made  so  clear  to  us  that  we  now  call 
them  Newton's  Laws,  namely: 

First  Law:  If  no  force  acts  upon  a  body  in  motion  it  con- 
tinues to  move  uniformly  in  a  straight  line.  Formerly  men 
imagined  that  a  body  must  be  continuously  pushed  to  keep 
it  moving.  Now  we  know  that  force  is  needed  to  stop  it. 
Ordinarily  the  force  applied  is  friction,  but  if  a  body  moves 
with  little  friction  over  a  smooth  surface,  as  in  skating,  a 
single  push  causes  it  to  travel  a  long  distance. 

Second  Law:  If  force  acts  on  a  body  it  produces  a  change 
of  motion  proportional  to  the  force  and  in  the  same  direction. 

Third  Law:  When  a  body  exerts  force  upon  another  body 
it  experiences  an  equivalent  reaction  from  the  latter. 

The  results  of  these  laws  were  long  known,  but  the  prin- 
ciple was  not  understood.  When  David  killed  Goliath,  as  we 
read  in  the  Bible,  he  shot  a  little  stone  at  him  from  a  sling. 
He  knew  that  if  he  swung  the  sling  around,  the  pebble  would 
be  held  back  by  the  sling  that  only  allowed  it  to  go  a  certain 
distance  from  his  hand,  but  as  soon  as  it  was  released  it  did 
not  fly  in  a  circle,  but  in  a  straight  line.  Here  we  have  New- 
ton's first  law;  and  the  sling  represented  the  force  which 
caused  the  pebble  to  apply  the  second  law  and  change  its 
direction. 

Again,  the  fact  of  gravitation  was  known  long  before  New- 
ton studied  it.  Many  an  object  must  have  fallen  upon  a 
philosopher's  head  before  Newton  was  aroused  by  his  mythical 
apple,  and  we  have  experiments  by  Galileo  that  showed  a 
pretty  clear  notion  of  the  law  of  gravitation  as  regards  terres- 
trial objects.  That  all  objects  are  attracted  equally  to  the 
earth  cannot  be  shown  unless  we  remove  obstructions  from 


SIR  ISAAC  NEWTON  105 

their  path.  The  buoyancy  of  the  air  will  affect  light  masses 
more  than  dense  ones;  if  the  air  be  removed  all  substances  will 
fall  to  earth  with  equal  rapidity.  Newton's  great  step  was  the 
extension  of  the  idea  of  gravitation  to  celestial  objects;  and 
he  claimed  that  all  masses  attract  each  other  at  all  times,  but 
that  distance  influences  the  intensity  of  this  attraction. 

By  means  of  Newton's  generalization  astronomers  have  been 
able  to  calculate  the  mutual  attraction  of  the  various  planets 
for  each  other  and  for  the  sun.  The  more  closely  celestial 
bodies  approach  one  another,  the  more  they  affect  each 
other's  motions;  with  the  help  of  Newton's  law  these  irregu- 
larities in  the  orbits  have  been  explained.  The  matter  has 
been  carried  even  further;  from  such  perturbations  of  Saturn, 
Leverrier  was  able  to  predict  the  existence  of  the  then  un- 
known planet  Neptune,  and  to  tell  owners  of  better  tele- 
scopes than  he  possessed  where  to  look  for  it. 

Again,  Newton  was  the  first  to  explain  the  tides,  and  to 
show  how  they  were  due  to  the  action  of  the  moon  and  the 
sun  upon  the  ocean,  although  the  larger  body,  the  sun,  is  so 
much  farther  from  the  earth  than  is  the  moon  that  its  attrac- 
tion is  less  apparent.  The  moon  appears  to  revolve  around  the 
earth  once  in  about  twenty-four  and  one  half  hours,  whereas 
the  average  interval  between  the  successive  appearances 
of  the  sun  is  twenty-four  hours.  The  solar  tide  and  lunar  tide 
therefore  pursue  unequal  rates.  On  the  occasions  when  they 
come  together  we  have  the  high  or  spring  tides.  When  they 
oppose  each  other  we  have  the  low  or  neap  tides. 

More  practical  still  were  Newton's  discoveries  in  optics. 
Telescopes  had  been  made  by  Galileo  and  others  before 
him,  but  the  lenses  employed  were  imperfect  owing  to  the 
difficulties  in  the  manufacture  of  glass,  and  the  light  in  pass- 
ing through  them  showed  queer  colorations.  The  images 
were  blurred  and  surrounded  by  colored  fringes.  It  is  only 


106  MORRIS  LOEB 

in  recent  days  that  all  these  imperfections  have  been  cor- 
rected, and  we  now  have  glass  lenses  of  forty  inches'  diameter, 
as  in  the  great  Chicago  telescope.  But  Newton  invented  a 
telescope  which  was  quite  independent  of  glasses,  using  the 
principle  which  you  can  discover  for  yourselves  by  looking 
into  the  bowl  of  an  ordinary  tablespoon.  The  reflecting 
telescope  has  been  much  used,  and  the  highest  point  reached 
in  its  construction  was  Lord  Rosse's  instrument,  which  was 
fifty  feet  long,  six  feet  in  diameter,  and  possessed  a  mirror 
weighing  six  tons. 

Yet  another  practical  device  comes  even  more  closely 
home  to  us.  Navigators  are  indebted  to  Newton  for  the  in- 
strument next  in  importance  to  the  compass,  —  the  sextant. 

The  chromatic  errors  of  lenses  led  Newton  to  study  the 
nature  of  light  so  profoundly  that  he  not  only  avoided  the 
errors  of  his  predecessors  but  also  profited  by  them.  Allowing 
a  beam  of  sunlight  to  pass  through  the  round  hole  of  a  shutter 
and  fall  upon  a  prism,  he  found  that  it  was  broken  up,  and 
that  in  place  of  a  single  white  dot  it  became  a  streak  of  various 
colors.  From  this  he  inferred  that  white  light  is  not  simple  but 
consists  of  various  rays  that  can  be  separated  by  a  prism.  He 
attempted  to  recompose  the  light  out  of  the  colors  into  which 
he  had  dissociated  it,  and  found  here  again  that  he  was  suc- 
cessful. From  this  discovery  of  Newton's  there  have  been 
distinct  advances  in  later  times.  It  is  found  better  to  re- 
place the  round  hole  in  the  shutter  by  a  slit.  We  then  find 
that  white  light  is  decomposed  to  give  a  band  of  purer 
colors  than  that  obtained  through  a  round  opening.  It  is 
called  a  spectrum,  and  is  well  known  to  most  of  you.  This 
band  can  be  shown  to  be  made  of  little  images  of  the  slit 
placed  side  by  side.  Afterwards  Fraunhofer  showed  that  if 
the  slit  was  made  narrow  enough,  a  large  number  of  fine  lines 
appeared  across  the  spectrum.  And  later  still,  Bunsen  and 


SIR  ISAAC  NEWTON  107 

Kirchhoff  showed,  first,  that  each  chemical  element  emits 
certain  rays  having  fixed  places  in  the  spectrum,  and  sec- 
ondly, that  many  elements  emit  rays  that  coincide  in  their 
position  with  the  lines  discovered  by  Fraunhofer  in  the  solar 
spectrum.  From  these  coincidences  we  are  enabled  to  assert 
positive  knowledge  as  to  the  chemical  constitution  of  the  sun 
and  other  heavenly  bodies  far  beyond  the  reach  of  any  other 
known  method  of  analysis. 

Thus  Newton  seems  by  his  magic  touch  to  have  opened 
doors  to  mysterious  chambers  in  nature's  mansion,  some 
destined  to  become  workshops  for  man's  practical  needs, 
some  treasuries  of  his  mental  wealth.  Well  did  he  deserve 
the  eulogy  of  the  poet  Pope:  — 

"  Nature  and  nature's  laws  lay  hid  in  night, 
God  said, '  Let  Newton  be,'  and  all  was  light!" 


OLIVER  WOLCOTT  GIBBS1 

WHEN  Oliver  Wolcott  Gibbs  died,  on  December  9th,  1908, 
American  chemists  were  bereft  of  one  of  their  leaders, 
to  whom  they  could  look,  with  affectionate  respect,  as  a 
pioneer  in  research,  and  the  true  example  of  the  tireless  seeker 
after  truth,  withal  an  earnest  patriot  and  a  noble  gentleman. 
He  was  never  at  the  head  of  a  great  university  laboratory, 
and  the  last  twenty-five  years  of  his  life  were  spent  in  retire- 
ment from  all  academic  duties;  no  great  body  of  students 
is  left  to  mourn  the  loss  of  their  former  teacher.  He  wrote 
comparatively  few  papers  of  general  interest  and  no  books; 
he  shrank  instinctively  from  appearing  in  the  public  eye, 
and  the  idea  of  making  even  an  informal  after-dinner  speech 
was  hateful  to  him.  His  austere  demeanor  and  dignified  re- 
serve must  have  always  prevented  his  gaining  popularity 
with  the  masses,  even  if  his  tastes  had  not  led  him  to  prefer 
scholarly  seclusion.  To  what,  then,  shall  we  ascribe  the 
influence  which  he  wielded  in  the  world  of  chemistry,  so  that 
foreign  as  well  as  American  institutions  of  learning  delighted 
in  showering  honors  upon  him,  and  considered  themselves 
fortunate  if  they  could  obtain  his  cooperation  and  advice  ? 
Was  it  not  because  we  all  realized  that  this  was  a  true  High- 
Priest  of  knowledge,  a  guardian  of  the  sanctuary,  rather  than 
an  exploiter  of  its  mysteries;  one  who  could  read  without  an 
accusing  pang,  that  beautiful  distich  in  which  Schiller  says 
of  Science :  — 

"  Einem  ist  sie  die  hohe,  die  himmlische  Gottin,  dem  Andern 
Eine  tiichtige  Kuh,  die  ihn  mit  Butter  versorgt." 

1  Reprinted  from  Proceedings,  Am.  Chem.  Soc.  (1910),  p.  69. 


OLIVER  WOLCOTT  GIBBS  109 

Gibbs,  a  man  of  modest  wants,  was  probably  always  pos- 
sessed of  such  means  that  he  could  restrict  himself  to  the  aca- 
demic side  of  his  profession,  and  his  family  traditions  and 
early  training  would  hardly  have  fitted  him  for  business.  I 
remember  conversations  with  him  about  the  successful  ca- 
reers of  his  friends,  A.  W.  Hofmann  and  Joseph  Wharton, 
which  made  it  clear  that  he  would  not  have  attacked  a  tech- 
nical problem  with  any  degree  of  confidence.  Perhaps,  there- 
fore, a  knowledge  of  his  own  limitations  may  have  assisted 
his  natural  predilections  in  determining  the  direction  of  his 
work  toward  pure,  one  may  almost  say  abstruse,  science. 
But  his  contemporaries  saw  a  man  seeking  truth  for  truth's 
sake,  and  they  put  their  trust  in  his  disinterestedness,  as 
well  as  in  his  scientific  acumen  and  experimental  skill.  Justly 
conscious  of  his  own  worth,  he  was  quick  to  recognize  what 
was  meritorious  in  the  work  of  others,  and  to  applaud,  without 
reserve,  the  advances  along  lines  quite  foreign  to  his  own  point 
of  view,  while  maintaining  an  almost  pathetic  veneration 
for  his  own  great  masters,  between  whom  and  the  present 
generation  he  remained  one  of  the  last  links.  Cant,  religious, 
moral  or  scientific,  was  abhorrent  to  him,  and  he  could  be 
cruelly  caustic  in  his  denunciation  of  what  he  deemed  charla- 
tanry or  insincerity.  On  the  other  hand,  where  he  once  placed 
his  trust,  he  left  it  implicitly,  and,  when  his  advice  and  help 
were  sought,  in  good  faith,  he  gave  of  his  best.  In  appearance, 
and  in  some  respect  manners,  he  resembled  James  Russell 
Lowell,  to  whom  I  believe  he  was  distantly  related.  It  would 
have  taken  considerable  boldness  to  be  flippant  in  his  presence, 
and  his  students,  at  all  periods  of  his  life,  seem  to  have  stood 
in  great  awe  of  him.  But  he  was  dearly  beloved  by  friends 
in  and  out  of  academic  circles,  and  he  seemed  to  have  the 
power  of  impressing  his  own  enthusiasm  upon  those  with 
whom  he  collaborated  for  the  public  good,  as  well  as  for  the 


110  MORRIS  LOEB 

advancement  of  science.  The  Union  League  and  Century 
Clubs,  of  New  York  City,  owe  their  foundation  largely  to  his 
efforts,  just  as  did  the  National  Academy  of  Science  in  Wash- 
ington; his  effectiveness  as  a  member  of  theU.  S.  Sanitary 
Commission,  during  the  Civil  War,  seemed  to  have  exacted 
the  lifelong  respect  of  all  his  associates. 

While,  therefore,  it  was  an  inestimable  gain  to  the  Law- 
rence Scientific  School  to  secure  this  master  of  research,  one 
cannot  help  wondering  whether  the  narrowness  which  kept 
him  out  of  his  own  alma  mater,  and  forced  him  to  leave  the 
city  of  his  birth,  did  not  curtail  some  of  his  most  useful  powers. 
Furthermore,  the  policy  which  subsequent  events  have  proved 
thoroughly  mistaken,  of  reducing  the  Lawrence  Scientific 
School  in  1871  from  its  status  as  virtually  a  graduate  faculty 
of  natural  and  exact  science,  to  a  shadowy  existence  as  an 
appendage  of  Harvard  College,  deprived  Professor  Gibbs 
of  his  teaching  laboratory,  and  barred  American  students  of 
chemistry  from  working  under  the  direction  of  a  guide  who 
remained  for  another  quarter  of  a  century  the  master  of  in- 
organic research.  In  fact,  during  less  than  eight  years  of 
his  entire  career  was  he  in  a  position  to  assign  topics  for 
independent  research  to  students  in  his  laboratory,  and  thus 
carry  out  those  parallel  tests  which  are  the  great  resource  of 
the  modern  university  professor.  Thus  it  is  that  the  figure 
of  Wolcott  Gibbs,  even  though  so  recently  faded  from  our 
eyes,  towers  in  our  memory  like  that  of  one  of  the  early 
frontiersmen  blazing  out  new  paths  in  a  primeval  forest; 
like  the  heroes  of  James  Fenimore  Cooper,  who  seek  the 
wilderness  from  love  of  nature,  not  from  hatred  of  man,  and 
who  are  solitary,  not  from  a  saturnine  disposition,  but  from 
lack  of  followers  willing  to  forsake  easy  harvest  for  the  chances 
of  a  laborious  chase. 

But  to  those  who  were  his  immediate  contemporaries, 


OLIVER  WOLCOTT  GIBBS  111 

Gibbs  could  not  have  appeared  as  a  recluse.  In  the  "Ameri- 
can Journal  of  Science,"  he  was  for  twenty-two  years  the 
eloquent  interpreter  of  the  trend  of  chemistry  to  workers 
in  other  fields  of  science,  and,  similarly,  the  early  volumes  of 
the  "Berichte  der  deutschen  chemischen  Gesellschaft"  con- 
tain his  concise  but  adequate  reports  of  the  achievements 
of  American  chemistry.  His  understanding  and  sympathy 
for  other  branches  of  exact  sciences  was  great,  and,  in  fact, 
thermodynamics  and  optics  received  much  of  his  attention: 
he  it  was  who  first  appreciated  the  work  of  his  namesake, 
J.  Willard  Gibbs,  and  insisted  on  the  award  of  the  Rumford 
Medal  for  that  treatise  on  "Equilibrium  in  Heterogeneous 
Systems,"  which  became  famous  twenty  years  later,  when 
Le  Chatelier  rediscovered  it  for  the  benefit  of  modern  chem- 
ists. I  could  instance,  from  personal  observation,  other 
judgments  rendered  by  him  on  scientific  matters  of  less  mo- 
ment, in  which  the  clearness  of  his  vision  and  the  thoroughness 
of  his  examination  proved  that  no  accidental  circumstances 
led  him  thus  to  anticipate  the  trend  of  physical  thought. 
His  contemporaries  were  stimulated  both  by  the  ideas  which 
he  freely  placed  at  their  disposal,  and  by  the  appreciative 
discrimination  which  he  exercised  toward  their  own  scientific 
efforts. 

Born  in  New  York  City,  on  February  21, 1821,  as  the  second 
son  of  Colonel  George  and  of  Laura  Gibbs,  he  was  named 
after  his  maternal  grandfather,  Oliver  Wolcott,  Secretary  of 
the  Treasury  under  Washington  and  Adams.  His  boyhood 
was  chiefly  spent  on  his  father's  farm  at  Newtown  (near 
what  is  now  Astoria),  Long  Island,  and  he  was  educated  at 
the  Columbia  Grammar  School  and  Columbia  College,  from 
which  he  received  the  degrees  of  A.B.  in  1841  and  A.M.  in 
1844.  He  also  graduated  in  medicine  from  the  College  of 
Physicians  and  Surgeons  in  1845,  though  he  never  practiced 


MORRIS  LOEB 

as  a  physician.  His  taste  for  physics  and  chemistry  developed 
early;  he  published  one  or  two  papers  as  an  undergraduate, 
worked  with  Dr.  Robert  Hare  in  Philadelphia  in  1842,  and 
went  abroad  in  1845  to  specialize  in  chemistry,  under  Ram- 
melsberg  and  Heinrich  Rose  in  Berlin,  and  under  Laurent, 
Dumas,  and  Regnault  in  Paris.  Returning  in  1848,  he  lec- 
tured at  Delaware  College  and  the  College  of  Physicians  and 
Surgeons,  and  was  appointed  Professor  of  Physics  and  Chem- 
istry at  the  Free  Academy  of  New  York  City,  now  the  Col- 
lege of  the  City  of  New  York,  but  then  practically  of  high 
school  grade.  Here  he  taught,  chiefly  by  lectures  and  reci- 
tations, until  1863,  when  he  was  called  to  Harvard  to  fill 
the  Rumford  Professorship  on  the  Application  of  Science 
to  the  Useful  Arts,  then  recently  vacated  by  Eben  Horsford. 
Attached  to  this  professorship  was  the  Chemical  Laboratory 
of  the  Lawrence  Scientific  School,  but  this  was  consolidated 
with  the  College  Laboratory  in  1871,  under  Professor  J.  P. 
Cooke,  and  Professor  Gibbs  thereafter  limited  himself  to 
courses  in  Physical  Chemistry,  continuing  his  chemical  in- 
vestigations with  the  aid  of  paid  assistants. 

In  1887,  he  was  made  Professor  Emeritus,  and  retired  to 
Newport,  Rhode  Island,  where  he  had  always  spent  his  sum- 
mers on  property  long  in  the  possession  of  his  family.  Here 
he  built  a  small  laboratory,  overlooking  the  beach,  in  which 
he  continued  to  work  for  another  decade,  until  his  waning 
strength  warned  him  to  desist.  He  had  lost  his  dearly  loved 
wife,  Josephine  Mauran,  shortly  before  his  retirement  from 
Cambridge,  and  he  lived  very  quietly  at  Newport,  attended 
by  a  devoted  niece,  interesting  himself  chiefly  in  horticulture 
as  a  pastime.  He  had  little  taste  for  the  fine  arts,  but  was 
passionately  fond  of  nature  and  a  friend  of  all  living  things. 
I  vividly  remember  his  indignation,  one  day,  when,  in  the 
course  of  a  walk,  we  came  across  a  contractor  who  was  pre- 


OLIVER  WOLCOTT  GIBBS  113 

paring  to  lop  off  from  a  beautiful  old  tree  a  great  branch  that 
extended  into  a  street  through  which  he  wished  to  move  the 
villa  of  a  summer  resident.  When  the  man  refused  to  listen 
to  remonstrances,  I  was  left  to  guard  the  tree,  while  the  Doc- 
tor set  off  to  find  a  policeman  and  finally  routed  out  the 
Mayor  of  Newport,  with  the  result  that  the  house  had  a 
quarter  mile  more  to  travel  and  the  tree  was  saved. 

I  have  already  stated  that  Gibbs's  opportunity  to  teach 
advanced  chemistry  to  students  was  limited  to  eight  years: 
Professor  F.  W.  Clarke  has  given  an  authoritative  account 
of  his  teaching  at  this  period,  in  his  beautiful  lecture  before 
the  Chemical  Society  of  London.1  My  own  experience  came 
later,  when  I  fortunately  joined  the  very  small  class  which 
attended  the  course  in  Chemical  Physics  to  which  he  confined 
himself  after  1871.  The  formal  part  of  the  lesson  was  fre- 
quently dismissed  in  a  few  minutes,  in  which  he  handed  out 
his  full  lecture  notes,  to  be  copied  at  home:  the  remainder 
of  the  hour  was  devoted  to  experimentation  or  to  purely  in- 
formal discussion  of  problems  arising  out  of  the  general  topic. 
I  do  not  think  that  the  subject  was  ever  treated  exhaustively, 
but  we  all  felt  enriched  and  stimulated  when  the  hour  was 
over.  Unfortunately,  the  course  was  not  correlated  to  any 
other  work  in  the  University,  and  I  doubt  whether,  at  any 
one  time,  more  than  a  dozen  undergraduates  knew  Professor 
Gibbs  by  sight. 

Privileged,  half  a  dozen  years  later,  to  assist  him  at  his  pri- 
vate research  laboratory,  in  Newport,  I  was  able  to  observe 
more  closely  his  methods  of  thought  and  work.  He  belonged 
emphatically  to  what  might  be  termed  the  Berzelius  type  of 
chemist,  basing  his  views  upon  an  intimate  knowledge  of  the 
reactions  of  a  selected  number  of  elements,  and  preferring 
direct  deduction  from  qualitative  or  quantitative  evidence 

1  Journ.  Chem.  Soc.  Trans.  95,  1299  (1909). 


114  MORRIS  LOEB 

to  the  experimental  substantiation  of  a  hypothesis  reached  by 
inductive  speculation.  His  synthetic  researches  were  chiefly 
carried  out  in  test  tubes,  without  overexact  measurements 
of  reacting  quantities,  of  temperature  or  other  conditions. 
The  elaborate  search  for  an  optimum  production  of  a  given 
compound,  so  familiar  in  recent  inorganic  work,  did  not  ap- 
peal to  him,  and  he  frequently  emphasized  his  desire  to  point 
out  the  directions  in  which  complex  compounds  should  be 
sought,  leaving  their  careful  study  to  others.  Working  with 
the  simplest  apparatus,  almost  exclusively  in  aqueous  solu- 
tions, he  certainly  produced  an  astonishing  number  of  new 
compounds,  whose  correlations  he  was  able  to  point  out  with 
considerable  verisimilitude.  Perhaps  he  missed  a  reaction 
here  and  there;  but  few  of  his  critics  have  been  able  to  state 
that  they  failed  to  find  what  he  did,  when  they  followed  his 
directions  closely.  As  an  analyst,  he  enriched  us  with  some 
elegant  methods,  which  are  not  sufficiently  emphasized  in 
textbooks:  the  determination  of  manganese  as  pyrophos- 
phate;  the  use  of  mercuric  oxide  instead  of  a  fixed  alkali  in 
precipitating  various  acids  with  mercuric  nitrate;  improve- 
ments in  the  estimation  of  bases  as  sulphates  and  oxalates; 
the  detection  of  cerium  by  means  of  bismuth  tetroxide  or 
lead  peroxide;  the  use  of  luteocobalt  salts  to  characterize 
various  acids.  The  determination  of  metals  by  electrolysis, 
the  operation  of  difficult  fusions  downward  instead  of  upward, 
the  use  of  a  comparison  tube  in  eudiometric  measurements, 
were  all  methods  first  published  by  him,  and  many  methods 
developed  by  others  were  due  to  his  suggestions.  In  physics, 
he  early  remedied  defects  in  some  types  of  galvanic  cell,  now 
obsolete,  and  he  devised  improvements  of  considerable  value 
in  the  prism  spectroscope. 

A  curious  departure  from  his  customary  work  was  his 
reversion,  late  in  life,  to  physiological  chemistry,  when  he 


OLIVER  WOLCOTT  GIBBS  115 

undertook  in  1889  with  H.  A.  Hare  and  later  with  E.  T. 
Reichert  the  systematic  study  of  the  action  of  definitely  re- 
lated organic  compounds  upon  animals.  His  ideal  was  the 
establishment  of  principles  whereby  the  physiological  effect 
of  drugs  might  be  enhanced  or  modified  step  by  step,  so  as  to 
produce  gradations  of  physiological  effect  comparable  to  the 
shading  of  the  spectral  colors.  The  experimental  work  was 
done  by  his  associates,  and  did  not  progress  far  enough  to 
lead  to  definite  conclusions  upon  this  idea. 

The  name  of  Gibbs  will,  however,  be  chiefly  associated 
with  his  three  great  researches  on  the  cobalt-ammines,  the 
platinum  metals  and  the  complex  acids.  The  oxidation  of 
cobalt  in  ammoniacal  solutions  had  been  observed  by  Gmelin 
as  early  as  1822;  but  F.  A.  Genth  first  produced  well-defined 
salts  of  an  ammonia-cobalt  base  in  1847,  publishing  his  results 
in  1851,  in  which  latter  year  papers  were  published  in  France 
by  Claudet  and  by  Fremy,  who  defined  four  distinct  series. 
Gibbs  discovered  xanthocobalt  in  1852,  and  thereupon  asso- 
ciated himself  with  Professor  Genth,  then  at  the  University 
of  Pennsylvania,  in  a  thoroughly  systematic  study,  to  which 
Gibbs  seems  to  have  contributed  the  greater  portion  of  the 
experimental  detail.  The  results  were  published  by  the 
Smithsonian  Institution  in  December,  1856;  but  the  second 
series  of  the  work  was  presented  by  Gibbs  alone  to  the  Ameri- 
can Academy  of  Arts  and  Sciences  in  1874  and  1875.  These 
papers  are  noteworthy  for  the  thoroughness  with  which 
each  of  the  many  series  was  studied,  analytically  as  well  as 
synthetically;  he  not  only  showed  that  the  same  type  of 
cobalt-ammine  could  persist  through  various  combinations 
with  different  acids,  but  also  proved  that  certain  acid  groups, 
like  NO2,  must  be  frequently  considered  an  integral  part  of 
the  base,  and  that  this  was  notably  true  of  the  water,  con- 
sidered by  others  mere  crystal- water,  which  distinguished  the 


116  MORRIS  LOEB 

composition  of  the  roseo-  from  the  purpureo-cobalts.  His  re- 
searches were  the  natural  foundation  of  Werner's  theory, 
which  has  gained  general  recognition  during  the  past  fifteen 
years. 

Analogy  to  cobalt-ammines  appeared  to  exist  in  a  com- 
pound obtained  by  Fremy  in  1844,  by  the  action  of  ammoni- 
um chloride  upon  potassium  osmiate,  and  Gibbs  proved  this, 
in  a  brief  note  published  with  Genth  in  1857,  by  showing 
that  chlorine  could  be  replaced  by  other  negative  radicals 
without  altering  the  Os :  NHs  ratio.  In  his  final  paper,  in 
1881,  he  named  these  compounds  the  osmyl-tetrammine 
series.  But  he  was  deflected  from  the  continued  study  of  the 
ammines  of  the  platinum  group,  which  he  had  evidently  pro- 
posed to  himself  in  1858,  by  the  interest  which  the  separa- 
tion and  complete  characterization  of  these  metals  them- 
selves had  excited.  Working  chiefly  with  refractory  California 
ores,  he  found  it  necessary  to  develop  new  methods  of  attack, 
and  his  work  may  well  be  placed  by  the  side  of  that  of 
Claus  and  St.  Clair-Deville. 

Meanwhile,  the  platino-ammines  were  fully  studied  by 
other  observers,  and  Gibbs  rather  devoted  his  attention  to  the 
behavior  of  the  platinum  group  to  acids.  In  1877  he  found  that 
the  oxides  of  these  metals  would  unite  with  the  tungstates,  to 
form  the  salts  of  complex  acids,  analogous  to  the  silico-tung- 
states  of  Marignac,  and  this  was  the  starting-point  for  his 
great  researches  on  the  complex  acids,  which  virtually  mo- 
nopolized the  remainder  of  his  experimental  activity.  Begin- 
ning with  attempts  at  systematizing  the  straggling  data  on 
silico-tungstates,  phospho-tungstates,  etc.,  recorded  by  other 
observers,  through  the  preparation  of  parallel  compounds,  he 
was  led  to  draw  one  element  after  another  into  the  compli- 
cated molecules  that  gather  around  the  tungstic  or  molybdic 
nucleus.  With  a  large  corps  of  assistants  at  his  disposal,  the 


OLIVER  WOLCOTT  GIBBS  117 

work  would  have  assumed  gigantic  dimensions;  but,  with  a 
single  assistant  to  carry  out  the  most  subtile  quantitative  sep- 
arations, his  theories  must,  perforce,  await  mathematical  con- 
firmation, and  his  cabinet  must  contain  scores  of  unanalyzed 
compounds.  I  believe  that  he  regarded  the  tungstic  acids 
more  or  less  as  the  inorganic  analogues  of  hydrocarbons,  with 
certain  typical  arrangements,  into  which  other  groups  could 
enter  by  direct  substitution,  largely  merging  their  own  iden- 
tity. Probably,  the  majority  of  modern  investigators  ascribe 
a  more  important  r61e  to  these  elements  of  lesser  atomic 
mass;  but  viewed  from  the  standpoint  which  I  have  indicated, 
the  work  of  Gibbs  will  show  a  remarkable  consistency,  just 
as  his  experimental  data  will,  undoubtedly,  be  confirmed  in 
all  essentials  by  the  work  of  his  successors. 

And  thus  the  American  Chemical  Society  may  well  inscribe 
among  its  immortals  the  name  of  an  honorary  member,  with 
the  words  of  one  of  his  favorite  authors:  — 

"Wer  es  den  Besten  seiner  Zeit  hat  gleich  gethan 
Der  hat  gelebt  fur  alle  Zeiten." 


THE  CHEMISTS'  CLUB,  NEW  YORK1 

THE  Club  occupies  the  lower  portion  of  the  new  Chemists' 
Building,  at  50-54  East  41st  Street,  completed  in  March, 
1911.  This  building  occupies  a  lot  56  feet  by  100  feet,  in  the 
immediate  vicinity  of  the  Public  Library  and  the  Grand 
Central  Station.  It  is  owned  by  a  stock  company  whose 
shareholders  are  chemists,  manufacturers  and  companies  em- 
ploying chemical  processes,  and  it  is  to  be  conducted  for  the 
furtherance  of  chemical  industry  and  research:  in  certain 
eventualities,  The  Chemists'  Club  can  acquire  ownership  of 
the  building.2  The  five  uppermost  stories  —  not  controlled 
by  the  Club  —  are  constructed  for  chemical  laboratories. 

The  Club's  quarters  may  be  described  as  follows:  The  ves- 
tibule opens  into  a  large  oak-paneled  entrance-hall,  one  side 
of  which  serves  as  an  office,  the  other  as  a  lounging-room; 
a  wide  corridor  leads  thence  to  the  main  stairway  and  to  the 
auditorium,  which  occupies  the  entire  rear  half  of  the  lot. 
This  auditorium  seats  300  persons  and  has  a  lecture  plat- 
form completely  equipped  for  scientific  demonstrations  :  it  is 
decorated  in  classic  style,  and  is  a  very  lofty  and  well-pro- 
portioned room. 

The  upper  floors  of  the  Club  House  are  reached  by  a  very 
beautiful  stairway,  quite  independent  of  the  public  stairway 
and  elevators.  The  first  landing  leads  to  the  auditorium  bal- 
cony and  also  to  the  lavatories.  Then  comes  the  first,  or  social, 
floor,  the  front  half  of  which,  a  mahogany  room  52  by  23  feet, 
is  furnished  for  general  social  purposes;  in  the  rear  is  the 

1  Reprinted  from  the  Year  Book  of  the  Club  for  1910-11. 

2  Dr.  Loeb  himself  was  the  largest  shareholder,  and  in  his  will  left  his  holdings 
to  the  Chemists'  Building  Company  for  cancellation,  thus  very  materially  reducing 
the  amount  of  stock  to  be  acquired  by  the  Club.  [EDITOR.] 


THE  CHEMISTS'  BUILDING, 
52  EAST  FORTY-FIRST  STREET,  NEW  YORK 


THE  CHEMISTS'  CLUB,  NEW  YORK     119 

restaurant,  with  a  roof -garden  for  summer  use.  The  adja- 
cent spacious  pantry  is  connected  by  dumb-waiters  with  the 
kitchen  and  supply-rooms  that  are  situated  in  the  basement. 
For  Club  banquets  the  entire  floor-space  is  available.  The 
second  story  is  known  as  the  Scientific  Floor :  it  is  exception- 
ally lofty,  to  accommodate  a  gallery  in  the  Library,  which 
has  the  same  dimensions  as  the  social  room,  immediately 
below,  and  whose  shelves  can  hold  upwards  of  16,000  volumes, 
with  additional  space  in  reserve.  This  room  is  named  Chand- 
ler Hall,  after  the  first  president  of  the  Club,  and  it  will  prove 
an  ideal  work-room  for  the  scientific  student.  The  rear  half 
of  this  floor  is  to  be  used  as  a  scientific  museum,  according 
to  a  plan  devised  by  a  committee  of  the  American  Chemical 
Society,  but  not  yet  fully  developed.  Out  of  it  there  opens 
the  board-room,  which,  in  conformity  to  the  character  of  the 
museum,  has  been  designed  in  imitation  of  an  alchemist's 
laboratory  and  adapted  to  the  preservation  of  specimens  of 
old  chemical  apparatus.  A  small  photographic  dark-room 
and  storage  for  unbound  pamphlets  are  likewise  to  be  found 
on  this  floor. 

The  fourth  and  fifth  stories  are  residential,  and  provided 
with  rooms  for  either  transient  or  permanent  occupancy. 
There  are  two  suites,  consisting  of  sitting-room,  bedroom  and 
bath-room,  with  a  private  corridor,  and  eighteen  other  bed- 
rooms, a  number  of  which  are  provided  with  private  bath- 
rooms. Each  suite  or  room  is  named  after  a  college  or  uni- 
versity, whose  alumni  have  furnished  it,  and  this  serves  to 
accentuate  the  academic  spirit  of  the  Club  membership.  The 
institutions  thus  commemorated  are :  Harvard,  Yale,  Prince- 
ton, Columbia,  Pennsylvania,  New  York  University,  Massa- 
chusetts Institute  of  Technology,  German  Universities, 
Cornell,  British  Schools  and  Universities,  Johns  Hopkins, 
University  of  Virginia,  University  of  Michigan,  The  College 


120  MORRIS  LOEB 

of  the  City  of  New  York,  Imperial  University  of  Japan,  Swiss 
Universities,  Western  Universities. 

All  the  floors  are  connected  by  telephone  with  the  central 
switch-board  on  the  entrance  floor,  and  the  same  board 
serves  the  tenants  of  the  laboratories  in  the  upper  stories. 

It  is  also  interesting  to  note  that  the  Club  controls  three 
small  laboratories,  named  in  memory  of  Wolcott  Gibbs, 
Robert  Bunsen  and  August  W.  v.  Hofmann,  which  are 
equipped  for  the  transient  use  of  Club  members.1  Applica- 
tions for  their  use  must  be  made  at  the  Club  office. 

1  To  these  the  Chemists'  Club  has  added  a  fourth  memorial,  consisting  of  the 
two  rooms  which  constituted  Dr.  Loeb's  laboratory.  This  is  known  as  the 
Morris  Loeb  Laboratory.  [EDITOR.] 


THE  CHEMISTS'  BUILDING1 

THE  opening  of  the  new  Chemists'  Building  in  New  York 
City  is  an  event  of  national,  rather  than  merely  local  signi- 
ficance, and  the  committee  in  charge  has  done  its  duty  by 
seeking  to  express  this  fact  in  the  programme  of  the  opening 
exercises.  The  social  comforts  of  The  Chemists'  Club  are  but 
an  incident  in  the  general  scheme,  and,  in  fact,  the  physical 
transfer  of  that  organization  from  its  present  quarters  to  the 
splendid  home  now  provided  for  it  must,  necessarily,  await 
the  completion  of  its  furnishings,  after  the  building  itself  was 
declared  ready  for  occupancy.  Hence,  the  Club's  festivities 
were  subordinated  to  the  dedication  ceremonies  of  the  build- 
ing, when  due  emphasis  could  be  laid  upon  the  serious  aims 
of  the  enterprise,  and  to  the  scientific  meetings,  under  the 
auspices  of  the  local  sections  of  our  Society,  the  American 
Electrochemical  Society  and  the  Society  of  Chemical  Indus- 
try. It  will  not  be  the  fault  of  the  speakers  at  these  meetings, 
if  the  general  public  fails  to  grasp  the  importance  of  chemis- 
try in  our  industrial  development,  and  also  as  a  branch  of 
pure  science.  We  ourselves,  and,  especially,  those  of  us  who 
do  not  dwell  in  New  York  itself,  or  its  immediate  vicinity, 
might  well  take  this  occasion  to  reflect  upon  the  practical 
significance  of  this  undertaking. 

Nobody  can  review  the  history  of  American  progress  dur- 
ing the  past  twenty-five  years  without  recognizing  how  much 
more  intimately  chemistry  is  enmeshed  in  the  general  econo- 
mic and  sociological  texture  than  a  quarter  century  ago. 
Then,  the  American  student  who  went  beyond  the  general 
chemical  courses  prescribed  for  all  freshmen  and  sopho- 

1  Editorial,  reprinted  from  Journ.  Ind.  and  Eng.  Chem.,  3,  205  (1911). 


MORRIS  LOEB 

mores  did  so  as  a  preparation  for  medicine  or  some  other 
recognized  profession,  or  with  the  definite  purpose  of  entering 
an  academic  career.  The  possibility  of  establishing  himself  as 
an  independent  chemical  analyst  or  expert  was  certainly 
never  placed  before  the  student;  and  the  works-chemist,  in 
the  eyes  of  the  industrial  world,  was  held  in  the  sort  of  regard 
which  may  be  likened  to  Lincoln's  estimate  of  the  value  of 
brigadier-generals,  when  he  remarked,  on  hearing  that  a 
Confederate  raider  had  cut  out  a  baggage  train  and  captured 
three  generals,  "I  can  make  a  brigadier  any  day,  but  mules 
cost  money."  Under  such  conditions,  chemistry  as  a  profes- 
sion could  have  slight  standing,  and  the  gregarious  needs 
of  its  votaries  were  amply  met  by  the  annual  "  meetings  " 
of  Section  C  of  the  American  Association  for  the  Advance- 
ment of  Science,  and  by  occasional  local  gatherings.  The 
reorganization  of  the  American  Chemical  Society  on  a  na- 
tional basis,  in  June,  1890,  presaged  the  change  which  seems 
to  have  followed  the  World's  Fair  at  Chicago.  We  need  not 
inquire  too  closely  whether  the  lean  years  following  the  finan- 
cial crisis  of  1893  caused  manufacturers  to  appreciate  more 
fully  the  value  of  chemical  control  of  their  processes,  or 
whether  the  exhibits  of  German  and  other  foreign  manufac- 
turers, coupled  with  the  demonstration  of  the  World's  Chem- 
ical Congress,  attracted  the  attention  of  the  American  public 
to  the  possibilities  of  the  development  of  a  true  chemical 
industry.  Whatever  share  these  or  other  influences  may  have 
borne,  the  result  may  be  strikingly  shown  in  a  circumstance 
connected  with  the  opening  ceremonies  of  the  Chemists' 
Building.  In  the  preface  to  Volume  xn  of  the  "Journal  of 
the  American  Chemical  Society,"  the  editor  estimated  the 
number  of  chemists  available  for  the  newly-formed  New  York 
Section  at  two  hundred;  twenty-one  years  later,  with  dupli- 
cates eliminated,  thirteen  hundred  invitations  were  sent  out 


THE   CHEMISTS'  BUILDING 

to  the  enrolled  members  of  the  New  York  local  sections  of 
the  three  large  chemical  societies. 

Of  course,  in  this  phenomenal  development  of  the  chemical 
profession,  America  is  merely  catching  up  with  European 
progress,  not  leading  it.  The  enormous  attendance  at  the 
recent  Triennial  Congress  of  Applied  Chemistry  was  well 
calculated  to  astonish  the  non-chemical  world;  and  if  the  ini- 
tiative taken  at  Chicago  in  1893  toward  convening  these  con- 
gresses is  to  our  credit,  the  contrast  between  the  two  hundred 
and  fifty  men  then  in  attendance  and  the  chemists  who  will 
crowd  New  York  in  October,  1912,  will  convince  America  not 
only  that  progress  has  been  made,  but  also  that  still  greater 
advances  must  be  accomplished  here,  to  keep  pace  with  chem- 
ical industry  abroad.  The  American  Chemical  Society  would 
not  fulfil  its  duty  toward  its  membership  by  holding  occasional 
meetings  and  publishing  the  proceedings  thereof;  it  must  af- 
ford them  a  means  for  the  prompt  publication  of  their  re- 
searches, as  well  as  for  their  information  upon  the  world's 
progress  in  pure  as  well  as  applied  science;  its  journals  must  be 
the  link  which  binds  the  isolated  worker  to  his  profession. 
But  there  are  still  other  needs;  the  relations  of  the  profes- 
sional chemist  toward  the  industries  must  be  established  on  a 
sounder  basis;  the  elimination  of  wasteful  methods  of  manu- 
facture through  chemical  control  must  be  advocated  more 
forcibly  and  pervasively;  chemical  industry  must  cooperate 
more  closely  toward  the  furthering  of  mutual  interests,  toward 
the  establishment  of  more  satisfactory  manufacturing  con- 
ditions, from  the  legal,  as  well  as  from  the  hygienic  and  eco- 
nomic aspect;  aids  must  be  devised  for  the  furtherance  of 
research,  along'industrial  as  well  as  purely  scientific  lines. 

All  of  these  ideas  have  been  expressed  atone  time  or  another 
by  the  promoters  of  the  American  Chemical  Society,  and  they 
were  also  in  the  minds  of  the  founders  of  The  Chemists'  Club 


124  MORRIS  LOEB 

of  New  York,  which  for  the  past  twelve  years  has  maintained, 
at  considerable  pecuniary  sacrifice  on  the  part  of  its  mem- 
bers, an  organization  in  which  the  social  features  were  in- 
finitesimal as  compared  with  the  furtherance  of  the  above- 
named  objects.  The  new  Chemists'  Building  represents  the 
concrete  embodiment  of  these  ideals,  and  the  participants 
in  the  Eighth  International  Congress  will  find  established  in 
New  York  City  the  first  building  devoted  to  the  furtherance 
of  chemical  science  and  industry  by  all  those  means  which 
are  not  distinctly  pedagogical.  This  is  a  somewhat  bold 
assertion,  but  it  will  bear  analysis. 

It  is  needless  to  descant  upon  the  advantages  to  be  derived 
from  a  well-equipped  social  club,  which  affords  an  attrac- 
tive gathering-point  for  the  local  chemist,  as  well  as  housing 
accommodations  for  the  non-resident  member.  But  it  might 
be  well  to  bear  in  mind  that  the  industrial  chemist  usually 
visits  New  York  for  professional  consultation,  or  for  the  dis- 
cussion of  important  business  propositions;  the  technical 
library  is  an  indispensable  tool  which  he  can  now  employ 
without  quitting  his  shelter.  Indeed,  if  a  problem  arises 
suddenly  that  requires  experimental  test,  the  laboratory  in 
which  to  try  it  can  be  obtained  with  no  more  formality  than 
that  needed  for  engaging  a  bedroom.  For  quite  a  number  of 
years,  The  Chemists'  Club  has  made  it  an  object  to  promote 
the  interests  of  young  chemists,  as  well  as  those  of  the  manu- 
facturer, by  maintaining  a  professional  employment  bureau, 
which  was  chiefly  hampered  by  the  lack  of  a  permanent 
office.  Could  this  not  be  established  in  the  new  Club-house 
in  such  a  manner  as  greatly  to  facilitate  the  establishment  of 
communication  between  the  dispenser  and  seeker  of  employ- 
ment? 

The  existence  of  a  complete  building,  devoted  solely  to  the 
interests  of  the  chemists,  will  probably  be  the  best  demon- 


THE  CHEMISTS'  BUILDING  125 

stration  to  the  American  public  of  the  importance  which  this 
profession  has  now  assumed  from  the  technical  standpoint. 
The  consulting  chemist,  housed  in  laboratories  for  his  own 
use,  can  well  expect  greater  consideration  than  the  man  who  is 
obliged  to  conduct  his  work  in  a  ramshackle  rookery,  or,  at 
best,  in  an  out-of-the-way  corner  of  a  general  commercial 
building.  But,  apart  from  any  mere  question  of  ostentation, 
the  business  man  or  manufacturer  frequently  fails  to  seek 
chemical  advice,  on  questions  of  real  importance,  from  igno- 
rance of  the  manner  of  setting  about  it  and  sheer  indolence  in 
ascertaining  it.  Many  do  not  even  seem  to  know  that  there  is 
such  a  man  as  a  consulting  chemist.  May  not  some  eyes  be 
opened  and  some  extravagant  waste  of  natural  resources  be 
avoided,  by  persistent  efforts  of  the  manager  of  this  central 
home  of  chemistry,  and  the  rule  of  thumb  be  replaced  by 
the  rule  of  scales? 

The  American  Chemical  Society  has  gradually  accumu- 
lated a  library  of  considerable  magnitude,  which  has  been 
deposited  of  recent  years  with  The  Chemists'  Club,  which  or- 
ganization has  acquired,  by  gift  and  purchase,  many  vol- 
umes of  its  own.  But  the  shelf -space  has  been  so  limited,  that 
but  few  of  the  books  were  accessible  and  even  then  could 
only  be  consulted  under  unfavorable  conditions.  In  the  mag- 
nificent " Chandler  Hall"  the  entire  library  will  be  available 
for  consultation  at  all  reasonable  hours.  It  is  also  planned 
to  establish  a  collection  of  duplicates,  to  be  loaned  freely  to 
reputable  chemists  throughout  the  country.  Here  again,  the 
provision  of  a  suitable  working-place  will  serve  not  merely 
the  local  interests,  but,  perhaps  even  more  effectively,  the 
scattered  outposts  of  chemical  endeavor. 

One  of  the  chief  disadvantages  under  which  the  American 
investigator  labors  is  the  difficulty  of  obtaining  research  ma- 
terial. The  German  or  French  experimenter  can  obtain, 


126  MORRIS  LOEB 

within  twenty-four  hours,  a  specimen  of  virtually  every  chem- 
ical substance  that  is  in  the  market:  the  American  depends 
upon  the  stock  of  two  or  three  importers,  which  must  neces- 
sarily be  limited  in  regard  to  the  rarer  preparations,  or  he 
must  import  directly,  with  inevitable  delays  in  transit  and 
especially  at  the  custom-house.  The  Chemical  Museum  is 
planned  to  obviate  this,  by  keeping  as  complete  a  collection  of 
substances  as  possible,  in  relatively  small  quantities,  it  is 
true,  which  will  be  loaned  to  investigators  who  require  mate- 
rial for  preliminary  investigation.  Such  a  preliminary  test 
may  go  far  towards  determining  the  course  of  a  research  and 
deciding  whether  it  is  worth  the  chemist's  while  to  procure 
larger  quantities.  But,  the  projectors  also  hope  to  induce  the 
American  chemists  to  deposit  with  the  Museum  samples  of 
all  new  substances  prepared  in  their  researches,  to  serve  a 
similar  purpose  as  do  type  specimens  in  a  museum  of  natural 
history  as  standards  of  comparison  for  future  investigators. 
Here  we  should  have  the  first  chance  of  facilitating  chemical 
research  in  America  by  cooperation,  instead  of  by  subsi- 
dizing individual  investigations.  It  will  take  some  time  to 
perfect  the  plans;  but  if  it  can  be  accomplished,  the  student 
in  a  Rocky  Mountain  college  will  be  within  as  easy  reach  of 
his  materials  as  his  fellow  in  a  large  city  of  the  East. 

We  have  detailed  some  of  the  more  striking  advantages 
which  the  new  building  is  expected  to  confer  upon  the  chemi- 
cal profession  as  a  whole,  as  well  as  upon  its  individual  vo- 
taries; is  it  an  exaggeration  to  characterize  the  constitution 
of  the  Chemists'  Building  Company  itself  as  a  new  era  in  the 
chemical  industry  of  our  country?  In  scanning  the  list  of 
shareholders,  we  find  representatives  of  nearly  every  impor- 
tant concern,  or  even  the  larger  companies  themselves;  but 
that  this  is  not  a  "trust,"  in  the  sense  so  obnoxious  to  the 
yellow  journalist,  is  demonstrated  by  the  conditions  of  the 


THE  CHEMISTS'  BUILDING  127 

partnership.  No  shareholder  can  receive  more  than  3  per 
cent  dividends,  and  the  surplus  cannot,  under  any  circum- 
stances, accrue  to  his  benefit  within  the  next  fifty  years. 
This  association,  therefore,  is  not  for  individual  profit,  but 
for  the  raising  of  the  standards  of  chemical  industry  and  re- 
search in  the  United  States.  If  we  recognize  what  the  Verein 
zur  Hebung  der  chemischen  Industrie,  founded  by  Hof mann 
and  Werner  Siemens,  has  done  for  Germany,  we  may  well 
hope  for  further  fruits  of  this  initiative  here.  Perhaps  this 
building  will  house  joint  laboratories  for  the  solution  of 
questions  affecting  all  manufactures  alike;  or  experimental 
stations  for  the  study  of  natural  products  not  yet  utilized; 
or  a  cooperative  bureau  of  standardization  for  analytical 
methods;  or  a  national  welfare  bureau  for  employees  in  chem- 
ical factories.  This  building  does  not  owe  its  erection  to  some 
benevolent  demigod,  extending  his  protecting  wing  over 
people  unable  to  care  for  themselves;  it  is  a  building  by  the 
chemists,  of  the  chemists,  and  for  the  chemists.  May  it  ever 
serve  as  an  exemplar  of  unselfish  patriotic  cooperation! 


ADDRESS 

AS  PRESIDENT  .OP,  THE  CHEMISTS'  BUILDING  COMPANY 
ON  THE  OCCASION  OF  THE  OPENING  OF  THE  CHEM- 
ISTS' BUILDING,  MARCH  17,  1911 » 

I  RISE  to  welcome  you  on  behalf  of  the  directors  and  stock- 
holders of  the  Chemists'  Building  Company,  and  to  thank 
you  for  the  interest  which  your  presence  indicates  in  the 
formal  opening  of  a  building  which  we  believe  to  be  the  first 
of  its  kind,  not  only  in  this  country,  but  on  earth.  It  is  true 
that  Berlin  possesses  in  the  Hofmann-Haus  a  home  for  the 
German  Chemical  Society  and  that  London  owes  to  the  mu- 
nificence of  the  late  Ludwig  Mond  its  Davy-Faraday  Labo- 
ratories for  Chemical  and  Physical  Research.  But  this  new 
building  in  which  you  find  yourselves  is  planned  to  serve 
under  one  roof  the  social,  intellectual  and  practical  needs 
of  the  chemical  profession  not  of  New  York  alone,  but  of  our 
whole  beloved  country. 

The  means  for  its  construction  have  been  furnished  by 
men,  many  of  whom  can  expect  to  share  to  but  a  slight  degree 
in  the  benefits  of  The  Chemists'  Club,  which  occupies  so 
much  of  its  floor  space.  These  shareholders  see  in  it  the  in- 
carnation of  some  of  the  ideals  that  led  them  to  the  pursuit 
of  chemistry,  pure  or  applied,  as  their  lifework. 

For,  strange  as  it  may  seem  to  the  layman,  who  has  seen 
the  ugliest  blots  on  a  landscape  designated  as  chemical  fac- 
tories, who  has  sniffed  with  disgust  a  chemical  odor,  has  been 
urged  to  believe  that  the  chemist's  shadow  contaminates 
pure  foods,  and  has  been  taught  in  school  that  alchemy 
spelled  fraud  and  sorcery,  our  science  is  one  calculated  to 

1  Reprinted  from  Met.  and  Chem.  Engineering,  9,  177  (1911). 


OPENING  OF  CHEMISTS'  BUILDING     129 

develop  the  ideal  side  of  human  nature,  and  the  chemist, 
more  perhaps  than  the  votary  of  natural  science  or  the  de- 
votee of  the  so-called  humanities,  is  led  to  an  intense  interest 
in  human  development. 

Our  science  aspires  not  only  to  know,  but  also  to  do.  On 
the  one  hand,  it  leads  us  to  delve  into  the  secrets  of  nature, 
in  the  minute  atom  as  well  as  in  the  far  distant  stars,  in  the 
living  cell  as  well  as  in  the  crystallized  relics  of  the  convul- 
sions from  which  this  earth  was  born;  on  the  other,  it  leads  us 
to  apply  this  knowledge  to  the  immediate  needs  of  man,  be 
it  in  safeguarding  his  health,  in  ministering  to  his  material 
or  esthetic  wants,  or  in  regulating  his  commerce  and  in  facil- 
itating his  utilization  of  the  earth's  resources.  These  many 
points  of  contact  with  nature  and  with  human  interest  will  be 
the  theme  of  the  eminent  men  whom  I  shall  have  the  privi- 
lege of  introducing  this  afternoon  and  will  be  illustrated  at 
greater  length  in  the  scientific  meetings  which  are  to  follow; 
it  is  enough  that  we  recognize  at  this  moment  that  this  ver- 
satility of  method  and  of  purpose  must  necessarily  enlarge  the 
viewpoint  of  the  chemist,  and  that  we  seek  therein  the  mo- 
tives for  the  ready  cooperation  in  the  present  enterprise. 

Our  shareholders  content  themselves  with  a  moderate  re- 
turn for  their  money  and  have  agreed  that  any  surplus  profits 
shall  accrue  to  the  benefit  of  chemical  science.  They  hope 
that  the  facilities  afforded  within  these  walls  will  redound 
to  the  benefit  of  mankind  and  the  prosperity  of  the  country. 

May  I  emphasize  the  word  "facilities"?  There  are  two 
ways  of  aiding  a  man  or  a  cause :  by  addition  to  the  income  or 
reduction  of  the  expense.  The  pecuniary  result  to  the  bene- 
ficiary may  be  the  same,  but  the  moral  one  is  far  different;  it 
is  not  only  the  beggar  who  is  pauperized  by  the  cash  gift  and 
uplifted  by  the  aid  which  enables  him  to  earn  his  own  live- 
lihood. Arts  and  sciences  may  be  stimulated  by  prizes  and 


130  MORRIS  LOEB 

scholarships  beyond  a  doubt,  but  the  relation  between  donor 
and  recipient  is  not  free  from  restraint,  and  the  probability 
of  human  error  in  the  selection  of  the  right  incumbent  makes 
the  method  a  wasteful  one  at  best. 

Far  better  is  it  to  remove  those  obstacles  which  hamper  all 
work  equally  and  are  felt  more  severely  by  those  whose  means 
are  restricted  and  who  have  not  yet  earned  the  recognition 
of  the  world  at  large.  The  laboratory*student  is  encumbered 
by  certain  restrictions  in  America  more  than  elsewhere.  The 
higher  price  of  commodities  affects  him  in  many  ways  besides 
the  higher  cost  of  living,  rent  of  laboratory,  installation  of 
equipment,  purchase  of  supplies,  salary  of  assistant,  acquisition 
of  books.  The  advanced  cost  of  labor  militates  against  the 
construction  of  certain  grades  of  apparatus  and  the  prepara- 
tion of  the  rarer  chemicals  in  this  country;  and  a  curiously 
unscientific  tariff  law,  while  pretending  to  lift  the  duty  from 
articles  required  for  educational  purposes,  practically  forces 
the  colleges  to  make  their  purchases  abroad  and  prevents 
American  dealers  from  carrying  an  adequate  selection  of  im- 
ported material.  It  is  no  exaggeration  to  state  that  this 
duty-free  importation  clause,  as  interpreted  by  the  United 
States  Treasury  Department,  forces  the  American  chemist  to 
wait  from  two  to  three  months  before  making  an  experiment 
for  which  he  could  obtain  his  material  in  two  or  three  days 
if  he  were  working  abroad. 

To  remove  these  disadvantages  in  time  and  cost,  to  provide 
easy  access  to  books  and  apparatus,  to  make  room  for  the 
independent  scientific  worker,  are  the  ideals  which  hovered 
before  the  eyes  of  those  who  planned  this  present  enterprise. 
Time  will  show  whether  they  can  all  be  realized,  but  what- 
ever is  done  in  this  beautiful  building,  which  we  are  about  to 
dedicate,  must  open  free  opportunities  to  all  and  show  favor- 
itism toward  none,  if  the  trust  imposed  upon  its  management 


OPENING  OF  CHEMISTS'  BUILDING     131 

be  administered  in  the  spirit  of  those  who  have  contributed 
toward  its  erection. 

A  library  of  the  highest  scientific  importance  and  a  mu- 
seum of  chemical  substances  will  be  available  for  every  rep- 
utable chemist;  laboratories  for  temporary  as  well  as  for  per- 
manent use  will  be  at  the  disposal  of  the  earnest  student; 
help  and  advice  will  be  extended  to  the  struggling  beginner; 
good  comradeship  and  hearty  cooperation  will  characterize 
The  Chemists'  Club,  and  this  auditorium,  soon  to  be  named 
after  the  first  great  chemist  of  American  birth,  will  ever 
minister  to  his  ideal  of  the  application  of  science  to  the  use- 
ful arts. 


THE  COAIr-TAR  COLORS1 

THE  term  "coal-tar  colors"  is  applied  to  coloring  matters 
artificially  prepared  from  coal-tar,  chiefly  from  the  hydro- 
carbons extracted  from  it. 

The  first  observation  of  a  colored  compound  of  this  class 
was  made  by  Runge  in  1834;  but  the  real  beginning  of  the 
great  modern  color  industry  dates  from  1856,  when  W.  H. 
Perkin  obtained  a  violet  dyestuff  by  oxidizing  impure  ani- 
line with  chromic  acid,  took  out  a  patent  for  it,  and  com- 
menced manufacturing  it  in  England.  Many  other  dyes  were 
subsequently  obtained  from  aniline  and  the  substances  related 
to  it,  by  A.  W.  Hofmann,  Griess,  Girard,  Lauth,  and  many 
others.  But  the  most  sensational  step  was  the  preparation 
by  Graebe  and  Liebermann  (1868)  of  a  natural  dyestuff  — 
viz.,  the  coloring  principle  of  madder-root — from  the  anthra- 
cene of  coal-tar.  In  1880  indigo  was  first  prepared,  not  from 
coal-tar  products,  but  by  a  purely  synthetic  method,  and  other 
natural  colors  have  since  been  prepared  in  a  similar  manner; 
so  that  natural  dyestuffs  reproduced  by  artificial  means 
need  not  necessarily  originate  from  coal-tar.  The  artificial 
indigo  and  alizarin  are  not  mere  substitutes  for  the  natural 
indigo  and  madder;  they  are  chemically  identical  with  them, 
and  surpass  them  in  purity,  and  their  adaptability  to  special 
methods  in  dyeing  and  printing  often  makes  them  even  more 
desirable.  But  as  the  cost  of  manufacture  is  high,  they  com- 
pete with  the  natural  products  on  about  equal  terms. 

The  color  industry  was  first  developed  in  England  and 
France,  but  the  more  thorough  technical  instruction  at  the 

1  Reprinted  from  the  New  International  Encyclopaedia  (Dodd.  Mead  &  Co.,  New 
York,  1912,  6,  74-77),  by  permission  of  the  Publishers. 


THE  COAL-TAR  COLORS  133 

German  universities  produced  a  body  of  skilled  manufacturers 
and  investigators  who  soon  took  the  lead.  At  present,  in 
addition  to  the  great  factories  near  Berlin,  Frankfurt,  Elber- 
feld,  and  Mannheim,  and  a  host  of  smaller  ones  in  various 
parts  of  Germany,  German  capital  controls  many  of  the 
establishments  in  France,  Russia,  and  other  countries.  The 
United  States  possess  few  independent  factories,  and  the  list 
of  their  products  is  rather  limited;  indeed,  American  dyers  ap- 
pear to  call  for  a  smaller  range  of  dyestuffs  than  those  of  other 
countries.  A  peculiar  development  of  the  last  fifteen  years  is 
the  extension  of  the  methods  of  the  dye  industry  to  the 
production  of  artificial  drugs,  such  as  antipyrin,  antifebrin, 
etc.,  many  of  which  are  manufactured  in  the  same  establish- 
ments which  control  the  dye  patents. 

CLASSIFICATION.  Artificial  colors  were  formerly  classified 
merely  according  to  the  sources  from  which  they  were  ob- 
tained. Thus,  many  of  them,  including  magenta,  "aniline 
blue,"  "aniline  green,"  "aniline  yellow,"  etc.,  were  grouped 
together  as  aniline  colors.  At  present  somewhat  different 
systems  of  classification  are  used  by  different  authors,  but  all 
systems  are  based  exclusively  on  the  chemical  constitution 
of  the  dyes. 

Many  attempts  have  been  made  to  find  a  general  answer 
to  the  question :  What  must  be  the  chemical  nature  of  a  car- 
bon compound  in  order  that  it  may  be  a  dye?  An  all-embrac- 
ing answer  to  this  question  has  not  yet  been  found.  But  ex- 
perience has  shown  that  the  true  dyestuffs  exhibit  peculiar 
groupings  of  the  constituent  atoms.  Such  "chromophore" 
groupings  produce,  however,  only  a  tendency  toward  color, 
but  not  necessarily  colors;  indeed,  many  compounds  con- 
taining them  are  perfectly  colorless,  and  the  majority  of  true 
dyes  become  colorless  if  deprived  of  the  small  amount  of 
oxygen  they  contain,  although  their  chromophore  groups 


134  MORRIS  LOEB 

may  not  be  in  the  least  affected.  If,  however,  a  chromo- 
phore  group  is  combined  with  certain  other  atomic  groups, 
the  result  is  a  dye.  For  example,  the  so-called  azo-group 
( — N=N — )  is  chromophoric;  the  compound  called  azoben- 
zene,  CeH6 — N=N — C6H5,  although  colored  red  and  evidently 
containing  the  azo-group,  is  not  a  dye;  but  it  becomes  one 
when  the  so-called  amido-group  (NH2)  also  is  introduced  into 
its  molecule,  the  compound  C6H5 — N=N — C6H4NH2,  called 
amido-azobenzene,  being  a  true  dye.  If,  instead  of  the  amido- 
group,  a  hydroxyl  group  (OH)  is  introduced,  the  result  is 
again  a  dye  (an  orange  one).  Further,  the  tints  of  dyes  are 
produced  by  variation  in  the  "substituting"  groups  which 
replace  hydrogen  in  the  primitive  molecule.  Thus,  the  in- 
troduction of  the  methyl  group  (CH3)  generally  increases 
the  violet  tendency;  the  phenyl  group  (C6H5)  produces  bluish 
tints;  the  naphthyl  group  (CioH7)  a  tendency  toward  brown- 
red,  etc.  The  relative  position  of  the  groups  likewise  plays 
a  large  part  in  the  determination  of  color.  But,  as  we  have 
already  observed,  a  definite  and  all-embracing  rule  does  not 
exist.  Frequently  compounds  must  enter  into  combination 
with  a  base  or  an  acid  before  they  will  fix  themselves  upon 
the  fibre,  and  then  the  tints  are  frequently  affected  by  the 
different  bases  or  acids  to  a  varying  degree.  For  example, 
alizarin  dyes  red  with  the  hydroxide  of  aluminum,  and  black 
with  the  hydroxide  of  iron. 

For  the  purposes  of  the  present  sketch,  the  coal-tar  colors 
may  be  grouped  in  five  classes:  viz.,  the  azo-colors;  triphenyl- 
carbinol  derivatives;  quinone  derivatives;  diphenyl-amine 
derivatives;  and  indigo  dyes. 

Azo-CoLORS.  The  characteristic  compound  of  this  class 
is  azo-benzene,  C6H5N=NCeH5,  already  mentioned  above. 
We  have  seen  that  the  introduction  of  either  NH2  or  OH  in 
place  of  a  hydrogen  atom  produces  a  coloring  matter — yellow 


THE  COAL-TAR  COLORS  135 

in  the  former,  orange  in  the  latter  instance.  Replacing  either 
or  both  of  the  phenyl  groups  (C6H5)  by  more  complex  hydro- 
carbon groups  deepens  the  tone  (with  a  tendency  toward  the 
redder  tints),  increases  the  affinity  for  fibres,  and  dimin- 
ishes the  liability  to  fade.  The  earlier  dyes  of  this  class,  such 
as  "aniline  yellow,"  "Bismarck  brown,"  chrysoidin,  etc., 
were  singularly  brilliant,  but  were  not  fast;  whereas  the 
browns  and  the  many  reds,  ranging  from  scarlet  to  purple, 
which  are  now  produced  under  the  names  of  ponceaux  or 
bordeaux,  congos,  quinoline  red,  etc.,  are  exceedingly  per- 
manent. In  manufacturing  this  class  of  dyes,  nitrous  acid  is 
allowed  to  act  upon  an  ice-cold  solution  of  the  salt  of  any 
primary  base  (like  aniline),  and  the  "diazo-salt"  formed 
is  allowed  to  act  on  another  base  or  a  phenol;  an  endless 
variety  of  combinations  is  thus  possible. 

TRIPHENYL-CARBINOL  DERIVATIVES.  These  represent  the 
first  discoveries  in  the  aniline  dyes,  and  some  of  them  are 
still  produced  on  the  largest  possible  scale.  The  fundamental 
compound  of  the  class  is  triphenyl-carbinol  (CeH^sCOH, 
and  its  derivatives  are  properly  subdivided  into  rosanilines, 
rosolic  acids,  and  phthalems. 

In  the  rosaniline  group,  two  or  three  amido-groups  (NH2) 
are  introduced  in  place  of  hydrogen  atoms  of  the  phenyls 
(C6H5).  The  di-amido-compounds  are  green;  the  fri-amido- 
compounds  are  red,  violet,  or  blue.  Strictly  speaking,  the 
compounds  thus  obtained  are  not  themselves  dyes,  but  are 
bases  which  must  first  be  combined  with  suitable  acids,  and 
thus  brought  into  a  soluble  form.  Their  salts  in  the  solid 
condition  are  beautifully  crystalline  bodies,  showing  colors 
quite  different  from  those  of  the  solutions,  and  having  pecu- 
liar lustres  like  those  of  beetles'  wings.  The  solutions  have 
very  intense  colorations  and  stain  animal  fibres  readily  and 
permanently,  although  they  do  not  fix  themselves  easily 


136  MORRIS  LOEB 

upon  cotton  or  linen.  They  are  the  most  brilliant  and  lively 
dyes,  but  are  strongly  affected  by  sunlight,  and  are  conse- 
quently less  useful  than  some  dyes  of  other  classes.  They  are 
generally  manufactured  by  oxidizing  processes  at  a  com- 
paratively high  temperature,  whereby  two  or  three  simpler 
compounds  are  welded,  as  it  were,  into  compounds  of  com- 
plex molecular  structure.  Thus,  in  the  manufacture  of  the 
well-known  magenta  dye  (a  tri-amido-compound)  approxi- 
mately equal  quantities  of  aniline,  ortho-toluidine,  and  para- 
toluidine  are  heated  from  8  to  10  hours  with  arsenic  oxide  to 
190°  C.,  in  large  iron  kettles.  A  very  thick  mass  results, 
which  can  be  extracted  with  hot  water,  and  the  compound 
thus  obtained  is  found  to  be  made  up  of  molecular  quantities 
of  aniline,  ortho-toluidine,  and  para-toluidine  chemically 
combined. 

Rosolic  acid  and  its  derivatives  are  made  by  the  condensa- 
tion of  various  phenols,  three  phenols  being  condensed  into 
one  compound  of  the  rosolic  acid  group,  just  as  the  bases 
are  condensed  into  one  compound  of  the  rosaniline  group. 
The  comparatively  few  dyes  of  this  group  give  various  shades 
of  red.  The  hydroxyl  groups,  and  hence  the  acid  character 
of  the  phenols,  remain  unchanged  in  the  products  of  conden- 
sation; the  latter  therefore  combine  with  bases,  and  then  they 
readily  go  into  solution. 

The  phthaleins  differ  from  the  rosolic  acids  in  so  far  as 
one  of  the  three  phenyls  of  the  triphenyl-carbinol  is  connected 
in  them  with  a  carboxyl  group  (COOH),  the  other  two 
phenyls  having  one  or  more  hydroxyls  apiece,  as  in  the  rosolic 
acids.  The  phthaleins  were  discovered  by  Adolph  von  Baeyer, 
and  are  chiefly  remarkable  for  the  fluorescence  of  their  alkali 
salts  in  solution.  They  are  prepared  by  heating  phenols  with 
phthalic  anhydride  and  a  little  sulphuric  acid;  when  resorcin  is 
taken  as  the  phenol,  a  very  well-known  compound  is  obtained, 


THE  COAL-TAR  COLORS  137 

which  has  been  called  fluorescein,  while  its  sodium  salt  is 
known  as  uranin.  Solutions  of  the  latter  are  yellow  by  trans- 
mitted light,  but  bright  green  by  reflected  light.  This  fluo- 
rescence is  so  intense  that  it  is  distinctly  noticeable  in  ex- 
tremely dilute  solutions;  so  that  this  salt  has  been  used  to 
trace  subterranean  watercourses  supposed  to  connect  two 
neighboring  bodies  of  water,  the  dye  being  thrown  into  one 
of  these  and  fluorescence  being  subsequently  noticed  in  the 
other.  The  potassium  salt  of  a  brominated  fluorescei'n  is 
eosin,  C2oH6O5Br4K2,  with  a  magnificent  red  and  yellow  fluo- 
rescence. These  fluorescences  disappear  on  the  fibre,  but 
eosin  and  analogous  substances  impart  very  brilliant  flesh- 
tints  to  silk  and  wool. 

THE  QUINONE  DERIVATIVES.   These  contain  the  charac- 
teristic nucleus  — 


and  are  almost  invariably  colored,  although  they  become 
suitable  for  dyes  only  when  they  also  contain  several  hy- 
droxyl  groups.  By  far  the  most  important  substance  of  this 
class  is  alizarin,  which  was  already  mentioned  as  identical 
with  the  active  principle  of  madder.  Anthracene,  a  coal- 
tar  hydrocarbon,  is  converted  into  anthraquinone  by  heat- 
ing with  potassium  bichromate  and  sulphuric  acid;  the  an- 
thraquinone is  acted  upon  by  fuming  sulphuric  acid,  and 


138  MORRIS  LOEB 

the  resulting  compound  is  melted  with  caustic  soda,  yielding 
a  sodium  salt  of  alizarin.  This  is  soluble  in  water  with  a  fine 
red  color,  but  does  not  fasten  upon  any  kind  of  fibre.  If,  how- 
ever, cotton  is  previously  impregnated  with  salts  of  alumi- 
num, iron,  or  chromium,  the  alizarin  will  form  insoluble  salts 
("lakes")  with  these  metals;  and  as  the  precipitation  occurs 
within  the  pores  of  the  fibre,  subsequent  washing  cannot  re- 
move it.  Colors  of  this  class  of  dyes  are  not  suitable  for 
silk  and  wool,  but  are  very  intense  and  permanent  when 
properly  applied  to  cotton. 

THE  DIPHENYLAMINE  DERIVATIVES.  These  include  many 
varieties  of  dyes,  such  as  the  indulins,  indophenols,  thiazins, 
etc.  Their  chemistry  is  too  involved  to  be  disposed  of  in  a 
few  words.  It  may,  however,  be  mentioned  that  their  char- 
acteristic groups  are  similar  to  anthraquinone,  excepting  that 
the  oxygen  of  the  latter  is  replaced  by  sulphur,  imido-groups, 
etc.  The  more  important  dyes  of  this  class  include  methy- 
lene  blue  and  aniline  black. 

INDIGO  DYES.  By  far  the  most  important  of  these  is  indigo 
itself,  a  vegetable  dye  obtained  from  a  tropical  plant  cul- 
tivated in  India  since  the  earliest  times.  The  sap  of  this 
plant,  when  fermented  under  conditions  excluding  oxygen, 
yields  indigo  white,  a  soluble  material  having  the  formula 
Ci6Hi2N2O2;  if  the  fermentation  proceeds  in  the  open  air,  in- 
digo blue,  Ci6HioN2O2,  is  produced.  This  substance  is  a  deriv- 
ative of  the  base  called  indol,  C8H7N,  which  occurs  ready- 
formed,  in  small  quantities,  in  many  animal  and  vegetable 
secretions.  It  can  be  prepared  artificially  from  aniline  and 
chloraldehyde.  When  indigo  was  found  to  consist  of  two  indol 
molecules  joined  together  and  oxidized,  the  clue  for  the  pro- 
duction of  artificial  indigo  was  at  hand.  It  has  since  been 
found  that  any  benzene  derivative  having  a  nitrogenous  group 
and  a  two-carbon  group  in  the  "ortho"  position  may  give  rise 


THE  COAL-TAR  COLORS  139 

to  the  formation  of  indigo.  The  first  practical  method,  devised 
by  Baeyer  in  1880,  involved  the  action  of  potassium  hydroxide 
on  ortho-nitropropiolic  acid;  but  many  other  methods  have 
been  devised  since  then,  such  as  the  action  of  melted  potas- 
sium hydroxide  on  bromacetanilid,  the  action  of  halogenated 
acetone  on  aniline,  etc.  Indigo  is  one  of  the  most  reliable  dye- 
stuffs,  both  as  to  brilliancy  and  permanency,  and  there  is 
little  difference  in  these  respects  between  the  natural  and 
artificial  products.  The  finished  compound  can,  however,  only 
be  used  after  reduction  to  the  soluble  indigo-white,  and 
this  makes  its  use  in  dyeing  and  printing  somewhat  cumber- 
some. In  some  of  the  methods  for  preparing  artificial  indigo, 
the  fibre  can  be  impregnated  with  one  ingredient  and  the  other 
applied  either  in  the  dye- vat  or  from  the  printing-rolls;  con- 
sequently, indigo  can  be  and  is  often  directly  prepared  in 
the  quantities  and  in  the  places  in  which  it  is  needed. 

LIST  OF  COLORS.  The  following  are  some  of  the  best 
known  commercial  coal-tar  colors,  their  molecular  formulas, 
and  the  principal  methods  employed  in  their  manufacture. 

Aldehyde  Green.  —  See  Aniline  Green  below. 

Aniline  Black,  C3oH25N3,  made  by  the  oxidation  of  aniline  with  mineral 
salts. 

Aniline  Blue  (triphenyl-rosaniline  hydrochloride),  CssHssNaCl,  made  by 
heating  rosaniline,  benzoic  acid,  and  aniline,  and  subsequently  adding 
hydrochloric  acid. 

Aniline  Brown,  Bismarck  Brown,  or  Phenylene  Brown  (triamidoazo- 
benzene),  C^HisNs,  made  by  the  action  of  nitrous  acid  on  metaphenylene- 
diamine. 

Aniline  Green,  or  Aldehyde  Green,  €221127^820,  made  by  the  action 
of  ordinary  aldehyde  on  an  acid  solution  of  rosaniline  sulphate  and  the  sub- 
sequent addition  of  sodium  hyposulphite. 

Aniline  Orange.  —  This  name  is  applied  to  various  compounds  made  by 
the  action  of  amidosulphonic  acids  on  phenols.  The  name  is  often  applied 
to  the  so-called  Victoria  Orange,  CrHeN^Os. 

Aniline  Red.  —  See  Fuchsin  below. 

Aniline  Scarlet,  Ci8HiSN2O4SNa,  made  by  the  action  of  diazoxylene  on 
naphthol-sulphonic  acid. 

Aniline  Violet.  —  See  Mauveih  below. 


140  MORRIS  LOEB 

Aniline  Yellow  (hydrochloride),  CizHjzNsCl,  made  by  the  action  of 
nitrous  acid  on  an  excess  of  aniline. 

Alizarin,  Ci4H8O4,  made  artificially  by  successive  treatments  of  anthra- 
cene with  chromic  acid  and  fuming  sulphuric  acid,  and  melting  the  product 
with  potassium  hydroxide.  Among  the  dyes  allied  to  alizarin  are:  Alizarin 
Black,  CioH6O4.NaHSO3;  Alizarin  Blue,  Ci7H9NO4;  Alizarin  Orange, 
C14H7NO6;  and  Alizarin  Violet,  or  Gallein,  C2oH10O7. 

Auramin  (hydrochloride),  CnH^NsOCl,  made  by  the  successive  action 
of  phosgene  gas  (carbon  oxychloride)  and  ammonia  upon  dimethyl-aniline. 

Aurantia  (ammonium  salt  of  hexanitro-diphenylamine),  C^HsNyO^. 
NH4,  made  by  the  action  of  nitric  acid  on  methyl-diphenylamine. 

Aurin,  CigH^Os,  made  by  the  action  of  oxalic  and  sulphuric  acids  on 
phenol. 

Benzaldehyde  Green.  —  See  Malachite  Green  below. 

Benzidine  Red.  —  See  Congo  Red  below. 

Benzopurpurins,  dyes  of  various  red  shades.  They  are  chemically  al- 
lied to  Congo  Red  (which  see  below),  and  are  made  by  treating  salts  of 
toluidine  (which  is  made  from  nitrotoluene,  and  is  analogous  to  benzidine) 
with  nitrous  acid,  and  combining  the  resulting  salts  with  a-  and  /2-naph- 
thylamine-sulphonic  acids. 

Bismarck  Brown.  —  See  Aniline  Brown  above. 

Blackley  Blue.  —  See  Indulin  below. 

Bordeaux.  —  See  Ponceaux  below. 

Chryso'idin  (hydrochloride),  C^HisN^l,  made  by  the  action  of  diazo- 
benzene  chloride  on  metaphenylene-diamine  in  aqueous  solution. 

Congo  Red,  or  Benzidine  Red,  C32H22N6S2O6Na2,  made  by  the  action 
of  nitrous  acid  and  then  of  sodium  naphthionate  on  benzidine  hydro- 
chloride. 

Eosin,  C2oH605Br4K2,  or  C2oHeO5Br4Na2,  made  by  the  action  of  bromine 
on  fluorescem. 

Erythrosin,  C20H6O5l4Na2,  made  by  the  action  of  iodine  on  fluorescem. 

Fluoresce'in,  C2oHi2O5,  made  by  the  action  of  phthalic  acid  anhydride 
on  resorcin. 

Fwcfo^Rosaniline  Hydrochloride,  Magenta  or  Aniline  Red,  C2oH2oN3Cl, 
made  by  the  oxidation  of  toluidine  and  aniline  in  the  presence  of  acids. 

Gallem.  —  See  Alizarin  above. 

Helianthin.  —  See  Methyl  Orange  below. 

Indigo.  —  See  text  of  the  article  above. 

Indulin,  or  Blackley  Blue,  CisHisNs,  made  by  heating  aniline  salts  with 
amidoazobenzene. 

Magenta.  —  See  Fuchsin  above. 

Malachite  Green,  Benzaldehyde  Green,  or  Victoria  Green,  3C23H25N2C1. 
2ZnCl2  +  H20,  made  by  the  condensation  of  benzaldehyde  with  dimethyl- 
aniline,  and  the  subsequent  addition  of  hydrochloric  acid  and  zinc  chloride. 

Martius'  Yellow,  CioH5N2Q5SNa,  made  by  the  action  of  nitric  acid  on 
a-naphthol-monosulphonic  acid. 


THE  COAL-TAR  COLORS  141 

Mauvein  (hydrochloride),  or  Aniline  Violet,  CarHgsNiCl,  made  by  the 
action  of  chromic  acid  on  aniline  containing  some  toluidine. 

Methyl  Orange,  CwHiaNsSOsNa,  made  by  the  successive  action  of  nitrous 
acid  and  methylaniline  upon  para-amidobenzene-sulphonic  acid;  it  is  the 
sodium  salt  of  helianthin. 

Methyl  Violet,  C24H28N3C1,  made  by  oxidizing  dimethyl-aniline  with 
metallic  salts. 

Methylene  Blue,  CieHisNsSCl,  made  by  heating  amido-dimethylaniline 
with  sulphide  of  iron. 

Naphthol  Yellow,  CioH5N208SK,  made  by  the  action  of  nitric  acid  on 
a-naphthol-trisulphonic  acid. 

Nigrosin,  CigH^Ns,  made  by  heating  aniline  salts  with  nitrobenzene. 

Night  Blue,  C38H34N3O  (the  hydrochloride  of  this  is  the  commercial  dye), 
made  by  heating  pararosaniline  with  aniline  and  benzoic  acid. 

Pararosaniline  (chloride),  CigHigNsCl,  made  by  oxidizing  a  mixture  of 
para-toluidine  and  aniline  with  arsenic  acid,  or  nitrobenzene. 

Phenylene  Brown.  —  See  Aniline  Brown  above. 

Ponceaux,  or  Bordeaux.  —  Various  derivatives  of  azonaphthalene. 
"Ponceau  3R,"  Ci9Hi6N2O7S2Na2,  is  made  by  combining  diazocymene 
hydrochloride  with  /2-naphthol-disulphonic  acid. 

Primulin,  CnHi^^  (?),  made  by  the  action  of  sulphuric  acid  on 
thiotoluidine. 

Resorcin  Yellow,  or  Tropseolin  O,  C^HieNjjOsS,  made  by  the  action  of 
diazobenzene-sulphonic  acid  on  resorcin. 

Rhodamine  (hydrochloride),  C28H3iN203Cl,  made  by  the  action  of 
phosphorous  trichloride  on  fluorescein,  and  treatment  of  the  product  with 
diethylamine. 

Roccellin,  C20Hi3N2O4SNa,  made  by  the  action  of  /?-naphthol  on  the 
diazo-compound  of  naphthionic  acid. 

Rosaniline.  —  See  Fuchsin  above. 

Rose  Bengale,  C2oH4Cl2l2O5K2,  made  by  the  successive  action  of  chlor- 
ine and  iodine  upon  fluorescei'n. 

Rosolic  Acid,  C20Hi6O3,  closely  allied  to  aurin;  neither  aurin  nor  rosolic 
acid  is  specially  valuable. 

Safranin,  C2iH2iN4Cl,  made  by  the  oxidation  of  a  mixture  of  tolulene- 
diamine  and  aniline  or  toluidine. 

Tropoeolin.  —  This  name  is  applied  to  various  compounds  made  by  the 
successive  action  of  nitrous  acid  and  phenols  upon  amidobenzene  sul- 
phonic  acids.  See  Resorcin  Yellow  above. 

Uranin,  C2oGi0O5Na2,  the  sodium  salt  of  fluorescein  (which  also  see 
above). 

Victoria  Green.  —  See  Malachite  Green  above. 

Victoria  Orange.  —  See  Aniline  Orange  above. 

BIBLIOGRAPHY.  Schultz,  Die  Chemie  des  Steinkohlenteers  (Brunswick, 
1890);  Villon,  Traite  pratique  des  matieres  color  antes  artificielles  (Paris, 
1890) ;  Cazeneuve,  Repertoire  analytique  des  matieres  colorantes  artificielles 


142  MORRIS  LOEB 

(Lyons,  1893) ;  Schultz  and  Julius,  Systematic  Survey  of  the  Organic  Coloring 
Matters,  translated  by  Green  (New  York,  1894) ;  Hurst,  Dictionary  of  the 
Coal-Tar  Colors  (London,  1896);  Lefevre,  Traiti  des  matieres  color  antes 
organiques  artificelles  (2  vols.,  Paris,  1896) ;  Seyewetz  and  Sisley,  Chimie  des 
matieres  colorantes  artificielks  (Paris,  1897);  Benedikt,  Chemistry  of  the 
Coal-Tar  Colors,  translated  by  Knecht  (London,  1900) ;  Nietzki,  Chemistry 
of  the  Organic  Dyestiiffs,  translated  by  Collin  and  Richardson  (London, 
1892;  newer  German  edition,  Berlin,  1901).  An  annual  devoted  to  the 
progress  of  the  coal-tar  industry  has,  since  1877,  been  published  in  Berlin 
by  Friedlander,  under  the  title,  Fortschritte  der  Theerfarben-Industrie  und 
verwandter  Industriezweige. 


THE  PERIODIC  LAW1 

THE  name  "Periodic  Law"  is  given  to  the  generally  ac- 
cepted embodiment  of  the  relations  existing  between  the 
various  properties  of  the  chemical  elements,  so  far  as  they 
can  be  compared  with  one  another.  It  may  be  stated  as  fol- 
lows :  //  the  elements  are  arranged  in  the  order  of  their  atomic 
weights,  each  of  their  properties  varies  as  a  periodic  function 
of  the  atomic  weight. 

Ever  since  the  work  of  Richter,  Proust,  and  Dalton  had 
established  the  idea  of  fixed  numerical  values  attaching  to 
the  ingredients  of  compounds  (an  idea  which  was  deduced  by 
Dalton  from  the  hypothetical  existence  of  individual  atoms, 
identical  in  size,  mass  and  other  properties  for  any  one  ele- 
ment), chemists  sought  to  deduce  a  closer  relationship  be- 
tween the  various  elements  from  a  comparison  of  the  masses 
of  their  respective  atoms.  The  first  attempt  was  that  made  by 
Dr.  Prout  in  1815  to  prove  that  all  the  atomic  weights  were 
even  multiples  of  the  atomic  weight  of  hydrogen,  and  that 
the  latter  was  the  only  primitive  element,  from  which  the 
others  were  derived  by  processes  of  condensation.  It  was 
soon  found  that  very  few  elements  possessed  atomic  weights 
that  could  be  expressed  by  integers,  when  the  atomic  weight 
of  hydrogen  was  set  at  unity,  and  Prout's  law  was  gradu- 
ally modified  to  state  that  one  half  the  atomic  weight  of  hy- 
drogen, then  that  one-quarter,  should  be  taken  as  the  real 
standard.  Refinements  of  investigation  have  since  es- 
tablished the  relative  atomic  weights  to  the  second  place 
of  decimals,  and  it  can  now  be  asserted  that  the  number 

1  Reprinted  from  the  New  International  Encyclopaedia  (Dodd,  Mead  &  Co.,  New 
York,  1912,  15,  593-597),  by  permission  of  the  Publishers. 


144  MORRIS  LOEB 

of  exact  coincidences  with  Prout's  law,  as  compared  with 
that  of  deviations  from  it,  is  not  much  greater  than  what 
would  be  expected  by  the  theory  of  chances.  Prout's  law, 
has,  therefore,  been  practically  abandoned.  On  the  other 
hand,  interesting  relations  were  found  to  exist  between 
the  atomic  weights  of  similar  elements.  Thus  Doebereiner 
established,  in  1829,  his  so-called  triads,  sets  of  three  closely 
related  elements  whose  atomic  weights  were  approximately 
in  arithmetical  progression,  as  lithium  (7),  sodium  (23),  and 
potassium  (39);  calcium  (40),  strontium  (88),  and  barium 
(136) ;  sulphur  (32),  selenium  (79),  and  tellurium  (127) ;  chlo- 
rine (35.5),  bromine  (80),  and  iodine  (127);  iron  (56),  nickel 
(57),  and  cobalt  (58).  These  triads  were  later  extended  to 
include  longer  sets,  and  it  was  also  pointed  out  that  the  con- 
stant differences  were  in  many  cases  multiples  of  16,  the  atomic 
weight  of  oxygen,  whence  it  was  assumed  that  the  heav- 
ier elements  of  a  group  might  be  oxides  of  the  lightest,  thus 
reducing  the  number  of  primordial  elements  considerably. 
The  idea  of  connecting  all  the  atomic  weights  in  a  single 
progression  wherein  similar  elements  recurred  at  regular 
intervals  seems  to  have  first  struck  de  Chaucourtois,  and 
shortly  afterwards  Newlands;  but  the  law  in  its  complete 
form  is  due  to  Mendeleeff  and  Lothar  Meyer,  who  reached 
the  same  conclusion  independently  in  1869.  As  Mendeleeff's 
exposition  was  by  far  the  more  convincing,  he  has  been  given 
the  greatest  share  of  the  credit. 

A  good  idea  of  the  fundamental  principle  can  be  obtained 
from  the  accompanying  figure,  in  which  the  maximum  va- 
lencies in  the  elements  and  their  melting-points  are  shown 
to  be  periodically  related  to  the  atomic  weights.  The  latter 
are  laid  off  as  abscissas,  and  the  valencies  and  melting-points 
as  ordinates,  on  perfectly  arbitrary  scales.  It  will  be  seen 
that  the  two  curves  connecting  the  respective  points  are  un- 


THE  PERIODIC  LAW 


145 


dulatory,  with  well-defined  maxima  and  minima,  which  occur 
at  regular  intervals.  The  curves  for  most  of  the  other  prop- 
erties which  are  capable  of  precise  measurement  are  found  to 
have  a  similar  character;  the  maxima  and  minima,  of  course, 
do  not  always  coincide  with  the  same  elements  in  one  curve 
as  in  another,  but  the  elements  which  occupy  similar  positions 
on  one  curve  are  also  found  to  be  similarly  located  on  another. 
It  is  especially  noticeable,  moreover,  that  such  curves  indi- 
cate a  relationship  between  the  groups  of  elements,  as  well  as 
between  the  individual  elements  of  each  single  group.  Thus 
the  properties  of  the  alkaline-earth  metals  are  always  found 
to  be  intermediate  between  those  of  the  alkalies  and  those 
of  the  aluminum  group.  Breaks  in  the  continuity  of  the 
curves  indicate  lack  of  sufficient  experimental  data.  -t  .... 


Centigrade 


70     80      90     100    110    120   130    140    150    160   170  "180    190  200    21Q- 
ATOMIC  WBIAHTS 


The  arrangement  of  the  elements,  as  shown  in  the  accom- 
panying table  (p.  148),  is  the  one  generally  adopted  at  pre- 
sent, and  includes  all  the  well-known  elements.  An  asterisk 
marks  the  elements  discovered  since  1869.  Hydrogen  occupies 
a  unique  position,  and  is  generally  omitted  from  the  classifi- 
cation. Argon,  helium,  neon,  and  krypton  cannot  be  properly 
included  as  yet,  because  their  chemical  behavior  is  still  un- 
known. The  vertical  columns  include  the  elements  most 
closely  associated  with  one  another,  and  are  known  as  Groups 
I,  II,  etc. ;  horizontally,  we  have  the  Series  1,2,3,  etc.,  in  which 
the  similarities  are  not  great,  excepting  that  a  parallelism 
exists  between  the  elements  of  one  series  as  compared 
with  those  of  another.  The  elements  in  odd-numbered  series 
bear  a  closer  resemblance  to  one  another  than  they  do  to  the 


146  MORRIS  LOEB 

elements  of  the  intervening  even-numbered  series,  and  vice 
versa,  so  that  it  has  been  found  expedient  to  make  two  divi- 
sions of  each  group,  as  will  be  seen  in  the  table,  —  the  odd- 
numbered  series  being  set  upon  one  side,  the  even-numbered 
upon  the  other.  In  the  eighth  group  occur  triplets  of  closely 
analogous  elements  to  be  discussed  below.  Arrangements  into 
fifteen  or  more  individual  groups,  in  place  of  the  twin  and 
triple  groups  here  shown,  have  been  suggested,  but  not  gen- 
erally adopted.  Mention  should  also  be  made  of  the  fact  that 
this  table  can  be  constructed  by  writing  the  elements  in  the 
order  of  their  atomic  weights  along  a  screw-line  of  slight  pitch 
upon  the  surface  of  a  cylinder,  and  then,  as  it  were,  unrolling 
the  cylinder.  Various  efforts  have  been  made  to  connect  all 
the  atomic  weights  by  a  graphic  equation,  which  would  pro- 
vide for  an  arrangement  on  some  other  kind  of  a  spiral  curve, 
either  on  a  plane  or  in  space,  but  they  have  been  only  moder- 
ately successful. 

Before  proceeding  with  a  discussion  of  the  details  of  the 
table,  it  may  be  well  to  inquire  what  significance  can  be  at- 
tached to  this  periodic  variability  of  properties  as  functions 
of  the  atomic  weight.  The  many  attempts  to  connect  the 
atomic  masses  themselves  in  arithmetical  relations  would 
indicate  a  widespread  opinion  that  the  substances  now  called 
elements  are  really  compounds  of  simpler  substances,  whose 
particles  have  a  finite  mass  and  represent  individuals  of  dis- 
tinct chemical  properties,  so  that  the  chemical  elements  in 
each  of  the  periodic  groups  might  be  likened  to  one  of  the 
"homologous  series"  of  organic  compounds.  This  view  really 
antedates  the  periodic  law,  but  fails  in  large  measure  to  ac- 
count for  the  resemblance  existing  between  adjacent  members 
of  different  groups.  Many,  especially  Sir  William  Crookes, 
have  held  that  the  atoms  are  really  fortuitous  agglomerates 
of  an  indifferent  primordial  element,  and  that  atoms  of  ap- 


THE  PERIODIC  LAW  147 

proximately  the  same  mass  behave  similarly  because  they  vi- 
brate similarly,  while  atoms  of  greater  mass  might  vibrate 
harmoniously  with  the  smaller  ones.  It  is  difficult  to  explain, 
according  to  this  hypothesis  of  the  "genesis  of  the  elements," 
why  their  number  should  be  as  limited  as  it  is.  But  some 
facts  are  known,  vaguely  pointing  to  the  idea  that  the  atoms 
of  elements  within  the  same  periodic  group  are  capable  of 
vibrating  at  harmonically  related  rates,  and  that  the  great 
majority  of  chemical  and  physical  properties  depend  upon 
atomic  vibrations.  It  may,  however,  be  argued  that  just  as 
violin-strings  may  be  composed  of  different  materials  and 
yet  vibrate  together  according  to  common  laws,  so  may  the 
elements  be  composed  of  as  many  individual  materials  and 
still  exhibit  a  periodic  recurrence  of  properties,  if  the  latter 
depend  upon  the  harmonic  vibrations  of  the  atoms.  Until 
much  additional  proof  has  been  brought,  the  periodic  law, 
while  furnishing  a  vague  indication,  cannot  be  taken  as  posi- 
tive evidence  of  the  qualitative  unity  of  matter. 

In  the  table  it  will  be  found  that  the  first  group  contains  the 
univalent  elements,  the  second  group  those  which  are  divalent, 
and  so  on  up  to  the  seventh,  where  the  maximum  valency  is 
seven.  The  maximum  valency  of  the  elements  of  the  eighth 
group  may  be  set  at  eight,  but  their  compounds  rarely  ex- 
hibit so  high  a  valency,  and  in  many  other  respects  this  eighth 
group  is  rather  anomalous  and  is  taken  as  a  transition  group 
between  the  seventh  and  the  first.  Thus  the  three  elements, 
copper,  silver,  and  gold  belong,  with  respect  to  many  of  their 
properties,  especially  when  uncombined,  in  the  eighth  group; 
but  their  valency  is  usually  low,  and  many  of  their  salts  are 
so  similar  to  those  of  sodium  that  it  is  often  found  expedient 
to  place  them  in  the  first  group,  in  the  positions  occupied  in 
the  table  by  their  names  inclosed  in  parentheses.  The  va- 
lencies refer  especially  to  the  stable  oxides.  Stable  compounds 


3     • 

" 


nga 
65. 


Vanadium 
51.4 


Columbi 
93.7 


Uranium 
239.6 


ndium' 
44.1 


!«* 

38 

o 


Yttrium* 
8.9 


Erbium 
166.3 


Lithi 
7. 


Rubidi 
85.4 


Is 


<»H3s     ~ 


THE  PERIODIC  LAW  149 

of  hydrogen  occur  only  in  the  fourth,  fifth,  sixth,  and  seventh 
groups,  four  atoms  of  hydrogen  combining  with  one  of  each 
element  of  the  fourth  group,  and  this  amount  decreasing 
until  we  find  the  halogens  in  the  seventh  group  univalent 
toward  hydrogen.  The  first  group  includes  the  most  electro- 
positive elements,  and  there  is  a  steady  transition  toward 
the  electro-negative  end  of  the  series  in  the  seventh  group, 
while  the  eighth  group  shows  a  rather  sudden  return  toward 
the  electro-positive  side.  The  majority  of  the  compounds 
derived  from  elements  at  the  left  end  of  the  table  are  soluble, 
colorless,  and  volatile,  whereas  these  properties  change  from 
left  to  right  until  we  find  the  maximum  of  insolubility,  color, 
and  resistance  to  heat  in  the  lower  right  hand  of  the  table. 
It  is  also  possible  to  select  analogous  compounds  of  the  differ- 
ent elements  and  find  those  of  similar  properties  falling  within 
a  well-marked  zone  upon  the  chart.  Mendeleeff,  in  his  origi- 
nal essay,  added  the  following:  (1)  The  elements  which  have 
the  lowest  atomic  weights  are  those  most  widely  distributed 
in  nature,  and  also  represent  the  most  typical  characteristics 
found  in  the  second  series  of  the  table;  (2)  the  atomic  weight 
determines  the  character  of  an  element;  (3)  from  a  considera- 
tion of  their  position  in  the  system  new  analogies  can  be  dis- 
covered between  elements;  (4)  it  may  be  expected  that  new 
elements  should  be  discovered  to  fill  blank  spaces  within 
the  table,  and  their  properties  can  be  predicted  from  a  con- 
sideration of  those  of  the  adjacent  elements;  (5)  errors  in  the 
assumed  atomic  weights  may  be  detected  through  an  irregu- 
larity in  the  position  of  the  element  in  the  periodic  system. 
All  of  these  statements  have  been  verified,  and  the  im- 
mediate acceptance  of  Mendeleeff' s  views  was  facilitated 
especially  by  the  sensational  discovery  of  a  number  of  ele- 
ments whose  properties  agreed  accurately  with  those  pre- 
dicted by  Mendeleeff.  Thus  gallium,  germanium,  and  scan- 
dium had  been  completely  described  with  respect  to  their 


150  MORRIS  LOEB 

own  properties  and  those  of  their  compounds  before  they 
were  actually  discovered.  Success  has  also  attended  the  at- 
tempts to  correct  atomic  weights  in  several  cases  where  the 
elements  appeared  misplaced  in  the  original  tables  and 
were  assigned  to  positions  more  in  accordance  with  their 
properties,  but  necessitating  the  assignment  of  new  atomic 
weights.  The  weakest  point  of  the  table  lies  in  the  position 
of  tellurium,  which  should  fall  into  the  sixth  group,  but  is 
found  to  have  a  higher  atomic  weight  than  iodine,  which  un- 
doubtedly belongs  to  the  same  series  in  the  seventh  group. 
Efforts  to  explain  this  discrepancy  have  so  far  been  unavail- 
ing. There  are  also  a  number  of  elements  derived  from  the  so- 
called  rare  earths  whose  place  in  the  system  is  not  readily  as- 
signable. In  the  latter  case,  however,  it  may  be  said,  as  well 
as  in  that  of  the  atmospheric  gases,  argon,  helium,  neon,  and 
krypton,  that  their  properties  and  atomic  weights  are  not  so 
well  established  as  to  cast  doubt  upon  the  theory  through 
their  failure  to  coincide  with  it.  One  interesting  result  of  the 
theory  is  that  of  limiting  the  probable  number  of  chemical 
elements  to  about  120,  since  the  actual  number  of  blank 
spaces  is  limited,  and  since  it  is  extremely  unlikely  that  any 
elements  remain  to  be  discovered  with  an  atomic  weight  less 
than  that  of  hydrogen  or  greater  than  that  of  uranium. 

Among  the  physical  properties  which  appear  as  periodic 
functions  of  the  atomic  weight  may  be  mentioned  the  densi- 
ties of  the  uncombined  elements  and  of  their  oxides,  fusi- 
bility, atomic  volume,  crystalline  structure  of  the  compounds, 
coefficient  of  expansion,  refractive  index,  conductivity  for 
heat  and  electricity,  color,  and  velocity  as  ions. 

As  an  indication  of  some  purely  chemical  periodicities  the 
following  conspectus  has  been  arranged,  in  which  the  elements 
are  indicated  by  their  positions  in  the  above  table,  and  are 
generally  enumerated  in  such  order  that  the  one  which  shows 
the  property  in  the  most  marked  degree  has  precedence.  The 


THE  PERIODIC  LAW  151 

maximum  valency  of  the  elements  toward  oxygen  is  indicated 
throughout  by  the  Roman  numeral  of  each  group,  omitting 
the  "peroxides,"  in  which  the  oxygen  appears  to  be  linked  in 
a  different  manner. 

Maximum  valency  toward  hydrogen  in  stable  volatile  compounds:  — 

Univalent:  VII;  2,  3,  5,  7;  powerfully  acid  hydrogen  compounds. 

Divalent:  VI;  2,  3,  5,  7;  faintly  acid  hydrogen  compounds. 

Trivalent:  V;  2,  3,  5,  7;  basic  acid  hydrogen  compounds. 

Quadrivalent:  IV;  2,  3,  5;  neutral  acid  hydrogen  compounds. 
Maximum  number  of  hydroxyls  in  basic  compounds :  — 

One:  I;  1,  2,  3,  6,  8.   Ill;  11.  VIH;  6  (c  and  d). 

Two:  II;  2,  4,  6,  8,  3,  5,  7,  11.  IV;  11.  VIII;  4  (bed). 

Three:  III;  3,  4,  5,  6,  7,  8,  10,  12.  V;  11.  VII;  4.  VIII;  4a. 
Minimum  valency  in  oxygen  acids:  — 

One:  VII;  3,  5,  7. 

Three:  V;  2,  3,  5,  7.  VI;  3,  5,  7. 

Four:  IV;  2,  4,  3,  5,  7,  11. 

Five:  V;  4,  6,  10. 

Six:  VI;  4,  6,  10.  VH;  4.  VIII;  4a. 
Tendency  to  liberate  hydrogen  from  water  below  red  heat:  — 

I;  2,  3,  4,  6,  8.   II;  2,  3,  4,  6,  8.  VIH;  4a. 
Tendency  to  liberate  oxygen  from  water:  — 

VII;  2,  3,  5. 
Elements  whose  chlorides  are  unstable  toward  water:  — 

V;  3,  5,  7,  11,  4,  6,  10,  12.  VI;  10,  6,  4. 

Elements  whose  sulphides  can  be  precipitated  from  dilute  acid  solu- 
tion :  — 

VHI;  4d,  6  (abed),  10  (abed).  II;  11,  7.  HI;  11,  7.  IV;  11,  7,  5. 

V;  11,  7,  5.  VI;  12,  10,  6. 
Ability  to  form  alums  with  the  sulphates  of  I;  2,  4,  6,  8:  — 

III;  2,  4,  6,  10.  VI;  4.  VII;  4.  VIII;  4a. 
Ability  to  form  volatile  compounds  with  organic  radicles :  — 

With  one  methyl  group:  I;  3.  VII;  2,  3,  5,  7. 

With  two  methyl  groups:  H;  3,  5,  7,  11.  VI;  2,  3,  5,  7. 

With  three  methyl  groups:  HI;  2,  3,  5,  7,  11.  V;  2,  3,  5,  7,  11. 

With  four  methyl  groups:  IV;  2,  3,  5,  7,  11. 
Ability  to  form  complex  bases  with  ammonia:  — 

VIII;  4  (cd),  6  (abed),  10  (abed).  VI;  4.  II;  3,  11. 
Consult:  Newlands,  On  the  Discovery  of  the  Periodic  Law  and  on  Rela- 
tions Among  the  Atomic  Weights  (London,  1884) ;  Huth,  Das  periodische 
Gesetz  der  Atomgewichte  und  das  naturliche  System  der  Elemente  (Frankfurt 
a.  O.,  1884) ;  Belar,  Das  periodische  Gesetz  und  das  naturliche  System  der 
Elemente  (Laibach,  1897);  Mendeleeff,  "The  Principles  of  Chemistry,"  in 
A  Library  of  Universal  Literature  (New  York,  1901);  Venable,  The  Develop- 
ment of  the  Periodic  Law  (Easton,  Pa.,  1896). 


THE  EIGHTH  INTERNATIONAL  CONGRESS 
OF  APPLIED  CHEMISTRY1 

WITHIN  a  few  weeks  will  occur  an  event  of  supreme  im- 
portance to  American  chemists  and  especially  to  those  inter- 
ested in  the  branches  of  our  science  to  which  this  Journal  is 
especially  devoted :  —  the  meeting,  in  Washington  and  New 
York,  of  the  International  Congress  of  Applied  Chemistry. 
Strictly  speaking,  this  is  not  the  first  time  that  such  an 
organization  has  met  on  American  soil,  since  the  first  im- 
petus to  the  plan  of  these  international  meetings  seems  to 
have  been  derived  from  the  sessions  of  foreign  and  American 
chemists  who  attended  the  Columbian  Exhibition  in  Chicago 
in  1893.  Every  World's  Fair  has,  in  recent  years,  been  ac- 
companied by  meetings  of  specialists  in  sciences  and  arts;  but 
it  must  be  remembered  that  they  bear  the  relation  of  what 
is  popularly  called  a  side-show  to  the  Exhibition  itself.  They 
are  more  or  less  haphazard  in  their  relation  to  the  general 
world  of  science,  and  there  is  no  continuity  of  management 
from  one  occasion  to  the  next.  The  various  international 
scientific  congresses  are  autonomous;  the  experiences  gathered 
at  one  meeting  are  utilized  in  the  preparation  for  the  next 
one;  special  problems  are  committed  to  the  care  of  qualified 
experts,  for  the  report  of  authoritative  opinion  to  the  next 
gathering,  and  the  way  is  paved  for  that  general  world-wide 
cooperation  in  the  advancement  of  knowledge  and  the  per- 
fection of  its  utilization,  which  has  been  within  narrower 
limits  the  chief  virtue  of  the  various  national  organizations. 

It  is  just  two  hundred  and  fifty  years  since  the  Royal 

1  Editorial,  reprinted  from  Journ.  Ind.  and  Eng.  Chem.,  p.  556,  1912. 


CONGRESS  OF  APPLIED   CHEMISTRY    153 

Society  was  incorporated  in  London,  —  with  the  sole  excep- 
tion of  the  Accademia  dei  Lincei,  probably  the  oldest  existing 
society  for  the  exchange  of  knowledge  between  the  devotees 
of  exact  and  natural  sciences.  For  nearly  two  centuries  these 
societies  were  not  only  close  corporations  but  also  practically 
local  clubs.  The  greater  diffusion  of  scientific  learning,  as 
well  as  the  increased  means  of  communication  by  railroad 
and  telephone,  led  to  the  establishment  of  national  associa- 
tions for  the  advancement  of  science  (with  more  liberal  terms 
of  membership)  having  the  added  feature  that  meetings  were 
never  held  twice  in  succession  in  the  same  city.  A  natural 
outgrowth  was  the  national  society  for  the  promotion  of 
some  particular  science.  Since  increased  specialization  soon 
made  it  impossible  for  anybody  to  follow  understandingly 
the  sessions  of  general  associations,  these  met  in  sections  — 
a  circumstance  which  led  to  the  development  of  a  yet  closer 
form  of  union  among  their  respective  members. 

Thus,  in  chemistry  at  least,  each  great  nation  now  possesses 
one  or  more  special  societies,  not  restricted  as  to  localities 
or  qualifications,  as  is  the  case  with  the  academy  or  institute, 
but  open  to  every  person  interested  in  the  science.  At  the 
last  annual  meeting  of  the  American  Chemical  Society  there 
were  assembled  as  many  members  as  would  have  been  deemed 
a  fair  attendance  for  the  entire  American  Association  for  the 
Advancement  of  Science,  not  very  many  years  ago.  It  is  un- 
necessary to  descant  here  on  the  advantages  of  oral  discus- 
sion, supplemented  by  the  pleasures  of  social  intercourse, 
which  make  these  general  sessions  so  attractive,  any  more 
than  it  is  important  to  point  out  the  same  gregarious  instinct, 
which  has  led  to  the  successful  institution  of  so  many  local 
sections,  with  their  well-attended  stated  meetings.  But  we 
must  emphasize  the  fact  that  local  chemical  societies  led  a 
very  precarious  existence  until  the  more  powerful  national 


154  MORRIS  LOEB 

organization  enabled  them  to  gather  strength  by  coopera- 
tion and  let  them  experience  the  stimulus  of  generous  rivalry. 

And  now  we  have  entered  into  a  new  era,  practically  with 
the  opening  of  the  twentieth  century,  that  of  the  utter  aboli- 
tion of  national  boundaries  so  far  as  scientific  endeavor  is 
concerned.  A  new  chemical  discovery  in  Paris  is  known  in 
London,  New  York  and  Tokio  in  far  less  time  than  was  con- 
sumed in  the  transmission  of  Priestley's  or  Cavendish's  com- 
munications to  the  Royal  Society  in  London,  and  the  time 
is  rapidly  passing  when  the  possession  and  guarding  of  a 
scientific  secret  could  be  deemed  a  national  advantage.  If  it 
be  deemed  conducive  to  international  amity  that  the  young 
men  of  all  nations  should  meet  at  the  Olympian  games,  in 
contests  of  brawn  and  motor-nerves,  how  much  more  impor- 
tant is  it  that  there  be  occasional  interchanges  of  thought 
and  knowledge!  And  yet,  we  wonder  whether  the  press  of 
New  York  will  afford  as  many  paragraphs  to  the  forthcoming 
International  Congress  of  Applied  Chemistry,  for  matter 
supplied  to  it  free  of  expense,  as  it  has  published  pages  of 
expensive  cablegrams  from  Stockholm?  We  do  not  expect 
any  mobs  of  frenzied  cheerers  to  throng  around  the  arena 
of  scientific  debate;  and  yet  we  know  that  the  impression 
which  our  foreign  visitors  will  take  home  of  the  progress  in 
American  science  and  scientific  industry  will  be  of  far  greater 
importance  to  the  esteem  in  which  our  country  will  be  held 
abroad,  than  the  number  of  cups  which  the  "  Finland  "  will 
bring  home  from  Stockholm.  Our  individual  responsibility 
in  this  Congress  is  as  great  as  our  individual  opportunity. 

To  meet  the  leaders  of  chemical  knowledge  and  of  chemical 
manufacture,  from  abroad  as  well  as  at  home,  to  listen  to  a  free 
exchange  of  thought  and  practical  experience,  are  privileges 
for  which  innumerable  chemists  have  traveled  to  Berlin,  Lon- 
don, Paris,  Vienna,  and  Rome.  We  all  now  have  these  chances 


CONGRESS  OF  APPLIED  CHEMISTRY    155 

at  home,  coupled  with  the  opportunity  to  benefit  by  free  and 
generous  criticism  of  whatever  we  may  desire  to  bring  to 
their  view.  In  chemical  industry,  at  least,  mediaeval  secre- 
tiveness  is  breaking  down  in  favor  of  frank  exchange  of  experi- 
ences. 

That  the  scientific  importance  of  the  approaching  Con- 
gress is  thoroughly  realized  may  be  gathered  from  the  fact 
that  upwards  of  six  hundred  papers  have  already  been  ac- 
cepted and  are  being  printed,  ready  for  distribution  at  the 
Congress  itself.  In  view  of  the  stringent  rules  of  acceptance 
which  have  been  adopted,  and  the  early  date  set  for  the  sub- 
mission of  the  papers  themselves,  it  would  probably  have 
been  easier  for  the  authors  to  secure  publication  in  the  jour- 
nals of  then1  respective  national  chemical  societies,  had  they 
not  recognized  the  paramount  claims  of  this  international 
scientific  gathering. 

The  American  committee  of  arrangements  is  bending  every 
effort  to  ward  making  the  sessions  agreeable  to  the  participants; 
they  are  particularly  anxious  to  make  this  Congress  memor- 
able for  the  promptness  with  which  it  shall  transact  its  busi- 
ness, the  smoothness  with  which  the  machinery  of  entertain- 
ing its  members  shall  revolve  and  the  completeness  with  which 
their  comfort  may  be  considered.  This  means  as  full  coopera- 
tion on  the  part  of  every  American  chemist  as  has  been  cheer- 
fully afforded  by  the  hard-working  members  of  the  various 
committees.  It  may  be  taken  for  granted  that  every  chemist 
who  can  get  away  from  his  work,  no  matter  in  what  part  of 
the  United  States  he  resides,  will  be  anxious  to  attend  the 
Congress,  not  only  for  the  selfish  reasons  already  stated,  but 
also  for  the  patriotic  one  of  adding  by  his  own  presence  to  the 
prestige  of  the  greatest  chemical  function  which  is  likely  to 
occur  here  for  many  a  year. .  .  . 


CHEMISTRY  AND  CIVILIZATION1 

THAT  invention  is  one  of  the  chief  factors  in  the  world's 
progress,  and  that  scientific  investigation  is  at  least  coordi- 
nate with  geographical  discovery  in  widening  the  bounds  set 
to  human  comfort  and  well-being,  are  assertions  which  may 
well  be  called  axiomatic.  To  discuss  the  influence  of  scientific 
discovery  upon  civilization  might  seem  a  sort  of  supereroga- 
tion, a  mere  rhapsody  on  man's  wit  and  energy;  even  the 
slightest  hint  that  all  invention  has  not  made  for  progress, 
industrial  or  cultural,  may  possibly  be  taken  as  the  mark  of 
black  pessimism  or  whimsical  conservatism.  Yet  no  other 
chain  of  events  has  proven,  on  nearer  view,  to  have  main- 
tained a  single  direction;  and  that  historian  is  not  deemed  un- 
patriotic who  recites  impartially  the  failures  as  well  as  the 
successes  in  his  country's  record,  especially  if  a  study  of  the 
darker  phases  may  lead  to  an  avoidance  of  future  pitfalls. 
Thus,  too,  not  every  scientific  theory  or  practical  invention 
must  necessarily  have  been  in  the  line  of  real  progress;  some 
may  have  led  to  the  squandering  of  nature's  bounty,  or  per- 
haps to  the  temporary  disregard  of  some  more  important 
line  of  research.  It  may,  therefore,  be  both  fruitful  and  in- 
structive to  attempt  a  closer  study  of  the  ultimate,  as  well 
as  the  immediate  effects  of  such  innovations;  besides  obtain- 
ing a  more  stereoscopic  picture  of  an  important  branch  of 
human  activity,  we  may  derive  some  useful  lesson,  at  a  time 
when  the  gradual  exhaustion  of  the  earth's  stored  wealth  is 
giving  food  for  anxious  thought.  In  attempting  to  measure 

1  The  unfinished  introduction  to  a  projected  treatise ;  found  in  manuscript, 
1912. 


CHEMISTRY  AND   CIVILIZATION       157 

the  effect  of  a  scientific  invention  upon  civilization,  we  must 
proceed  rather  differently  than  would  the  historian  of  philo- 
sophic or  religious,  economic  or  political,  development.  In 
exact  science,  at  least,  no  hypothesis  can  be  so  erroneous  as 
to  work  practical  harm,  except  possibly  by  retarding  the  adop- 
tion of  a  correcter  view;  and  who  would  try  to  estimate  the 
amount  of  such  retardation?  Based  upon  the  observation 
of  solid  facts,  a  hypothesis  is  accepted  so  far  as  it  seems  to 
connect  them  with  one  another,  but  receives  scant  attention 
so  long  as  it  does  not  lead  to  equally  positive  results.  A  false 
ethical,  economic  or  political  theory  may  enjoy  universal 
credence  for  generations,  before  its  evil  effects  upon  the 
commonwealth  shall  have  been  recognized  and  corrected 
by  what  is  usually  termed  reformation  or  revolution.  Scien- 
tific thought  has  a  scarcely  perceptible  influence  upon  a  peo- 
ple; it  is  the  practice  by  which  they  are  helped  or  harmed. 
For  this  reason,  the  scientific  discoverer  must  be  content  to 
see  his  work  popularized  by  the  inventor,  and  the  Wollastons, 
Henrys  and  Hertzes  are  unknown  to  those  for  whom  Daguerre, 
Edison  and  Marconi  are  household  words. 

The  influence  of  a  scientific  invention,  put  to  practical  use, 
may  be  felt  in  various  directions:  it  may  assist  the  culture  of 
the  individual,  by  opening  up  new  channels  of  thought  or 
providing  new  means  of  aesthetic  enjoyment;  it  may  increase 
our  physical  comfort,  by  placing  in  our  hands  new  weapons 
wherewith  to  combat  hunger,  disease,  heat,  cold,  and  other 
elemental  forces;  it  may  modify  the  intercourse  of  individuals 
and  peoples,  by  devising  new  modes  of  communication  and 
transportation;  it  may  dislocate  political  relation,  by  creating 
more  potent  engines  of  offense  or  defense;  it  may,  tempo- 
rarily at  least,  profoundly  alter  the  commercial  prosperity  of 
whole  provinces,  creating  new  sources  of  wealth  in  one  local- 
ity, and  depreciating  the  product  of  another;  finally,  it  may 


158  MORRIS  LOEB 

have  a  share  in  determining  the  entire  problem  of  the  possi- 
bility of  human  existence  upon  this  earth,  on  the  one  hand  by 
promoting  a  more  efficient  utilization  of  natural  resources, 
on  the  other,  by  inducing  us  to  squander  futilely,  within  a 
lifetime,  material  that  has  been  accumulated  during  untold 
ages.  Rarely  will  close  analysis  permit  the  conclusion  that 
an  invention  has  wielded  only  one  kind  of  influence;  seldom 
will  no  interest  be  found  to  have  suffered  from  something  that 
has  produced  profit  and  enjoyment  for  the  multitude;  practi- 
cally never,  I  firmly  believe,  has  the  evil  preponderated  so 
largely  over  the  good,  that  a  corrective  could  not  be  applied 
in  time  to  prevent  an  irremediable  harm.  And  yet,  the  pop- 
ular mind  is  far  from  applying  true  standards  to  the  estimate 
of  certain  inventions,  that  have  been  hailed  as  the  achieve- 
ments of  our  era. 

Let  me  recite  a  few  examples,  in  illustration  of  my  last 
assertion,  without  treating  them  as  fully  as  if  they  came  en- 
tirely within  the  scope  of  my  inquiry. 

Is  it  not  generally  conceded  that  the  tremendous  gain  in 
individual  efficiency,  derived  from  the  introduction  of  tele- 
graph and  telephone,  is  offset  to  a  greater  or  lesser  extent  by 
an  increased  nervous  irritability  and  decreased  vitality?  Has 
not  the  diffusion  of  knowledge,  through  the  introduction  of 
the  power  press,  with  the  consequent  cheapening  of  printed 
matter,  been  accompanied  by  the  virtual  submergence  of 
good  literature  under  a  flood  of  ephemeral  reading-matter; 
just  as  the  typewriter,  with  all  its  advantages,  is  surely  un- 
dermining the  elegance  of  our  diction?  All  these  and  kindred 
inventions  have  vastly  facilitated  talking 'to  our  fellow-men; 
have  they  improved  the  quality  of  our  conversation  or 
strengthened  our  thinking-processes?  We  can  deny  this 
without  wishing  [for  one  moment  that  these  potent  aids  to 
communication  had  not  been  invented.]  .  .  . 


CHEMISTRY  AND   CIVILIZATION       159 

Dismissing,  as  incidental  to  a  mere  plaything,  the  reckless 
disregard  of  public  safety,  as  well  as  the  bad  manners  of  the 
"speeder,"  ought  we  not  to  realize  that  the  undoubted  en- 
joyment and  practical  convenience  of  automobiling  requires 
for  the  locomotion  of  the  single  individual  an  utterly  dispro- 
portionate amount  of  energy,  whether  we  measure  it  in  the 
conventional  horse  power,  or  in  the  stored-up  solar  energy 
represented  by  the  petroleum  burnt  up  for  the  propulsion, 
and  the  ores,  coal,  and  gums  utilized  for  the  construction  of 
this  modern  conveyance? 

Perhaps  the  motion-picture,  as  an  instrument  for  enter- 
tainment and  instruction,  is  too  novel  to  justify  an  estimate 
of  its  good  and  evil  effects;  some  hail  it  as  a  potent  aid  to  edu- 
cation, while  others  invoke  the  police  to  curb  its  power  to 
promote  immorality  and  vice.  It  is  thought  a  dangerous  com- 
petitor to  the  theatre;  though  we  may  well  doubt  whether 
its  rivalry  will  be  felt  by  the  higher  drama  so  much  as  by  the 
vaudeville  and  melodrama,  whose  decay  can  hardly  be  de- 
plored. But  the  economic  influence  of  these  cheap  and  all- 
pervasive  picture-shows  has  yet  to  be  estimated,  both  in  the 
amount  of  money  extracted  from  that  portion  of  the  popu- 
lation which  can  least  afford  it,  and  in  the  hours  diverted 
from  more  healthful  recreation,  as  well  as  from  gainful  occu- 
pation. 

Coming  to  a  far  more  serious  problem  of  world-wide  im- 
port, we  have  the  installation  of  those  modern  means  of  trans- 
portation which  have  so  vastly  extended  the  distance  from 
which  we  can  derive  food  and  commodities.  It  would,  of 
course,  require  years  of  study  by  a  trained  economist  to  evalu- 
ate all  the  effects  upon  commerce,  as  well  as  upon  the  sub- 
sistence of  urban  and  rural  population,  which  have  resulted 
from  the  gradual  removal  of  the  grain-farmer  and  stock-raiser 
from  the  neighborhood  of  the  consumer.  The  sociologist,  on 


160  MORRIS  LOEB 

the  other  hand,  must  recognize  the  difficulty  of  the  task  of 
tracing  the  influence  of  these  causes  in  encouraging  the  con- 
centration into  large  centers,  in  depleting  the  older  rural  com- 
munities of  their  more  energetic  elements,  and  in  eliminating, 
more  or  less  completely,  that  element  of  the  village  com- 
munity which  formed  the  connecting  link  between  city  and 
country  life  of  the  past;  while  he  hails  the  gradual  extension 
of  the  benefits  of  civilization  over  the  entire  earth.  Popular 
opinion,  pointing  to  the  reduced  price  of  food-stuffs,  clothing 
and  other  comforts,  to  the  freedom  of  migration  for  the  in- 
dividual, the  wage-earning  opportunities  for  the  myriads 
employed  in  the  carrying  trades,  will  unhesitatingly  answer 
in  the  affirmative  any  question  as  to  the  value  of  these 
modes  of  communication.  Public  opinion  on  this  topic  will 
doubtless  be  justified  at  that  time,  when  the  increased  popu- 
lation of  the  earth  will  demand  the  exploitation  of  all  its 
resources,  the  tilling  of  every  arable  field,  the  harnessing  of 
every  horse-power. 

At  the  present  juncture,  however,  the  physicist  cannot 
join  the  chorus  of  praise,  until  he  has  satisfied  himself  on  cer- 
tain points  that  come  more  closely  within  his  ken.  For  him, 
money  as  a  standard  of  comparison  must  'ever  be  secondary 
to  the  amount  of  energy,  —  in  the  dynamic  sense,  —  requi- 
site for  the  attainment  of  a  desired  object.  So  far  as  this  en- 
ergy has  a  market  value,  as  in  the  wages  for  day-labor  or  in 
the  price  of  fuel,  coin  may  form  a  temporary  expedient  for 
casting  a  balance,  —  less  reliable,  I  fear,  than  most  schools  of 
political  economy  will  admit. 

I  have  been  struck,  comparing  the  prices  of  certain  staple 
commodities,  as  a  bushel  of  wheat,  a  cow,  a  work-horse,  with 
a  laborer's  wage  in  ancient  Jerusalem,  imperial  Rome  and 
modern  New  York,  by  the  apparent  constancy  of  the  ratios, 
which  might  well  lead  us  to  look  to  departures  from  such  a 


CHEMISTRY  AND   CIVILIZATION       161 

fixed  mean,  —  whether  we  estimate  them  in  gold  or  in  day's 
work,  —  as  the  tone  measures  of  the  fluctuation  in  mundane 
prosperity.  But  if  we  go  to  over-populated  China  and  barely- 
settled  Alaska,  we  note  such  astounding  dislocations  of  these 
proportions,  that  we  realize  to  what  extent  their  apparent 
constancy  is  predicated  upon  the  equilibrium  between  natu- 
ral resources  and  man's  demand  thereon;  or  rather,  upon  such 
a  superabundance  of  these  resources,  that  human  consump- 
tion does  not  noticeably  affect  them.  During  the  twenty-five 
or  thirty  centuries  of  historic  times  preceding  the  nineteenth 
this  condition  was  maintained.  Our  forefathers  drew  their 
sustenance  from  the  surface  of  the  earth  and  consumed  rather 
less  than  was  derived  from  the  solar  energy  during  their  re- 
spective lives.  In  the  nineteenth  century  commenced  that 
wholesale  exploitation,  which  has  drawn  in  ever-increasing 
quantity  upon  the  stored-up  riches  of  the  earth's  interior.  So 
that  within  the  last  thirty  years  we  have  been  forced  to 
recognize  that  the  future  progress,  if  not  existence,  of  the 
human  race  is  threatened  by  the  gradual  exhaustion  of  our 
supplies  of  food  and  fuel.  Even  that  most  unreasoning  opti- 
mist, the  American  politician,  prates  of  the  importance  of 
conserving  our  natural  resources. 

The  great  break  in  the  continuity  of  dynasties  and  nations 
which  the  historian  entitles  the  French  Revolution  coincides 
more  or  less  closely  with  that  still  more  portentous  change 
in  human  history,  the  substitution  of  mechanical  methods  of 
manufacture  for  handicraft.  Simultaneously  began  the  de- 
velopment of  chemical  factories  to  which  the  historian  has 
paid  no  attention,  though  its  effect  reached  further  than  even 
the  political  economist  ordinarily  can  recognize.  There 
were  countless  revolutions  before  the  one  which  dethroned 
Louis  XVI,  and  man  had  learned  to  harness  animals,  wind 
and  water  to  replace  his  own  meagre  forces,  and  had  shaped 


162  MORRIS  LOEB 

tools  and  built  machines,  many  centuries  before  the  birth  of 
Watt  and  Arkwright.  Just  so,  many  operations  that  involve 
a  change  of  substance,  and  are  therefore  properly  classed 
among  chemical  processes,  had  their  origin  in  prehistoric 
times.  Ore-smelting,  tanning,  dyeing,  the  making  of  cement, 
pottery  and  glass  are  good  examples  of  industries  now  pe- 
culiarly within  the  chemist's  control,  but  which  were  prac- 
ticed by  rule  of  thumb,  by  skilled  artisans,  ever  since  the 
dawn  of  civilization. 

Then,  again,  the  preparation  of  perfumes  and  cosmetics, 
medicines  and  poisons,  had  been  perfected  long  before  the 
Roman  era,  and  these  arts  were  preserved  by  Jews  and  Arabs 
during  the  barbarous  relapse  of  mediaeval  Europe;  so  that 
there  was  a  constant  development,  from  the  magic  of  the 
Egyptian  priesthood,  through  the  alchemy  of  a  Geber  and  an 
Albertus  Magnus,  the  spagirism  of  a  Paracelsus  and  a  Glauber, 
to  the  chemistry  of  a  Becher  and  a  Boyle.  By  the  middle  of 
the  eighteenth  century,  scientific  chemistry  had  reached  a 
point  where  it  could  give  a  rational  explanation  of  some  of 
the  industrial  processes  of  the  period,  and  could  seek  to  con- 
trol their  operations  by  distinct  tests  and  to  improve  them 
upon  the  basis  of  laboratory  experiments.  But  the  essential 
step  toward  the  domination  of  scientific  theory  over  empir- 
ical manufacture  was  taken  when  Bergman,  Lavoisier  and 
their  contemporaries  recognized  the  constant  quantitative 
composition  of  chemical  substance;  for  now  it  became  certain 
that  the  proportion  of  ingredients  which  proved  most  ad- 
vantageous in  a  laboratory  experiment  must  be  the  ratio  to 
which  the  manufacturer  should  adhere;  the  percentage  of 
useful  substances  contained  in  raw  materials  from  various 
sources  could  be  estimated.  At  times  it  would  be  discovered 
that  certain  admixtures,  prescribed  for  centuries  by  tradi- 
tional formularies,  contributed  nothing  to  the  desired  com- 


CHEMISTRY  AND  CIVILIZATION       163 

pound,  and  could  be  omitted  with  the  same  impunity  as  could 
the  magic  incantations  of  the  alchemists. 

Lavoisier  perished  in  the  French  Revolution;  but  this 
same  political  upheaval  gave  an  indirect  impetus  to  chemical 
manufacture  in  the  modern  sense.  For  the  ensuing  wars,  with 
their  commercial  reprisals  which  cut  off  both  France  and 
England  from  their  existing  sources  of  supply,  stimulated 
attempts  to  substitute  artificial  for  natural  commodities,  and 
the  governments  offered  premiums  for  the  invention  of  pro- 
cesses which  would  manufacture  articles  at  home  that  were 
heretofore  imported  from  the  colonies  or  abroad.  Hence  arose 
the  beet-sugar  industry,  and  the  Leblanc  process  for  making 
artificial  soda,  to  replace  the  ashes  of  wood  and  seaweed  no 
longer  available  in  sufficient  quantities  for  the  making  of  glass, 
soap,  etc.  The  Leblanc  process,  however,  called  for  a  plenti- 
ful supply  of  cheap  sulphuric  acid  and  liberated  large  quan- 
tities of  hydrochloric  acid,  for  which  an  outlet  was  found  in 
the  production  of  chlorine  and  bleaching-powder  for  the  textile 
industries.  To  this  day,  soda  manufacture  and  its  allied  in- 
duction may  be  considered  the  foundation  of  all  chemical 
technology,  of  which  the  beet-sugar  process  is  the  first  example 
of  the  production  in  bulk  of  an  organic  compound  by  a  com- 
plicated series  of  steps  which  could  never  be  carried  on  suc- 
cessfully on  a  small  scale.  Up  to  the  end  of  the  eighteenth 
century,  chemicals  were  made  by  the  pound,  since  then  by 
the  ton. 

Of  course,  many  other  causes  have  succeeded  this  political 
impetus  as  stimulants  to  chemical  industry:  —  mechanical 
inventions,  in  connection  with  the  employment  of  steam  as 
a  motive  power;  the  influence  of  railroads  and  steamships  in 
facilitating  the  collection  of  raw  materials  and  finished  pro- 
ducts; the  discovery  of  great  ore-bodies,  of  petroleum  fields 
and  vast  coal-beds;  finally,  the  conversion  of  mechanical 


164  MORRIS  LOEB 

force  into  electricity,  whereby  water-power,  the  next  deriva- 
tive of  solar  energy,  becomes  available  as  a  constant  source 
of  light,  heat  and  chemical  action. 

Coal,  petroleum,  natural  gas  and  ores  have  accumulated 
within  the  earth's  crust  for  untold  ages.  Mankind  commenced 
to  draw  upon  this  supply  during  the  past  hundred  years  and 
is  already  considering  anxiously  its  approaching  exhaustion. 
Chemistry,  which  has  played  the  leading  part  in  this  sudden 
increase  of  consumption,  is  largely  concerned  in  the  effort  to 
restore  the  balance  which  has  been  disturbed. 

With  justifiable  confidence,  we  pin  our  faith  upon  the 
progress  of  scientific  discovery  and  invention.  We  should  not, 
however,  do  this  blindly,  but  seek  to  estimate  our  present 
accomplishments  at  their  true  value.  This  is  what  I  have  set 
out  to  do  in  the  present  volume;1  not,  indeed,  with  the  hope  of 
presenting  an  exhaustive  treatise,  but  of  stimulating  thought 
in  this  direction  and  of  leading  to  a  closer  inquiry  into  the 
steps  by  which  legislation  might  differentiate  the  industries 
which  promote  from  those  which  might  endanger  the  public 
good. 

For  this  purpose,  I  intend  to  follow  up  the  ramifications  of 
the  chief  industries  affected  by  chemical  research  and  attempt 
to  trace  their  influence  upon  human  welfare,  partly  by  ascer- 
taining what  facilities  they  have  afforded,  partly  by  esti- 
mating what  consumption  of  energy  they  have  entailed,  and 
partly  by  showing  what  older  industries  they  have  displaced 
or  effaced.  .  .  . 

Local  conditions,  legislation,  trade  and  labor  combina- 
tions have  so  much  more  effect  upon  wages  and  living-con- 
ditions of  the  laborer,  than  has  the  progress  of  technical 
science,  that  this  subject  may  be  deemed  outside  of  the  pre- 

1  One  cannot  but  feel  poignant  regret  that  the  rest  of  the  volume  was  never 
written.  [EDITOR.] 


CHEMISTRY  AND  CIVILIZATION       165 

sent  field.  The  sanitary  side  of  factory-life  must,  however,  be 
considered,  from  time  to  time,  since  it  is  indeed  important  to 
know  whether  we  are  enjoying  certain  luxuries  and  comforts 
at  the  risk  of  life  and  happiness  of  our  fellow-men;  we  must 
surely  count  the  cost  of  human  life  as  seriously  as  the  ex- 
penditure of  fuel  and  horse  power. 

In  most  chemical  industries,  even  taking  into  account 
special  risks  from  poisoning  and  explosions,  hygienic  condi- 
tions are  probably  above  the  average  factory  standard.  In 
Germany  and  other  enlightened  countries,  intelligent  legisla- 
tion regarding  sanitation  and  employers'  liability  has  won- 
derfully diminished  those  "unavoidable  accidents"  which 
crowd  the  American  news  columns,  and  has  reduced  the 
toll  in  deaths,  sickness  and  lessened  vitality,  which  unfet- 
tered industrial  competition  still  exerts  in  our  own  country. 
Excepting  in  a  direct  tussle  with  nature,  there  should 
be  far  fewer  really  hazardous  occupations;  certainly,  the 
dangers  connected  with  chemical  manufacture  are  so 
well  known  that  the  proper  precautions  should  be  readily 
available. 

On  the  other  hand,  it  will  hardly  be  profitable  to  estimate 
accurately  the  question  of  the  influence  of  chemical  manufac- 
ture in  accelerating  the  much-deplored  flow  of  rural  popula- 
tion to  the  cities.  Doubtless,  every  factory  attracts  an  addi- 
tional force  of  laborers,  and  the  aggregate  pay-rolls  of  chemi- 
cal factories  must  contain  an  enormous  number  of  potential 
farmers.  For  instance,  it  has  been  said  of  the  beet-sugar 
factories  that  they  constitute  the  most  natural  transition 
from  farm  to  factory  work;  a  statement  which  is  apt  to  be  con- 
tradicted by  those  who  have  seen  farmers'  children  thronging 
the  cotton-mills  and  shoe-factories  of  New  England.  It  will 
be  admitted  by  those  who  deplore  the  townward  trend,  that 
chemistry  has  somewhat  atoned  for  the  laborers  whom  it 


166  MORRIS  LOEB 

has  lured  away  from  the  farm  by  its  gift  of  artificial  fertilizers 
and  by  the  increased  market  which  it  has  provided  for  various 
farm-products.  .  .  . 

[The  manuscript  ends  here,  although  the  essay  was  evidently  not  com- 
pleted.] 


PART  II 
ORIGINAL  EXPERIMENTAL  INVESTIGATIONS 


UEBER  DIE  EINWIRKUNG  VON  PHOSGEN 
AUF  AETHENYLDIPHENYLDIAMIN1 

VON  Hrn.  Prof.  HOFMANN  veranlasst,  habe  ich  die  Ein- 
wirkung  des  Phosgens  auf  Aethenyldiphenyldiamin  studirt 
und  bin  vorlaufig  zu  folgenden  Result  aten  gekommen. 

Die  genannte  Base  wurde  mil  fliissigem  oder  in  Benzol 
gelostem  Phosgen  8-10  Stunden  im  Einschlussrohr  auf 
80°  erhitzt.  Das  Rohr  zeigte  nur  geringen  Druck,  in  der 
Reaktionsmasse  hatte  sich  viel  Anilinchlorhydrat  ausge- 
schieden;  mil  Benzol  und  Aether  konnte  eine  Substanz  isolirt 
werden,  welche  aus  Alkohol  in  Krystallen  anschoss. 

War  mehr  als  1  Mol.  Phosgen  auf  2  Mol.  Base  angewandt 
worden,  so  enthielt  das  Produkt  Chlor,  bildete  kleine  Nadeln 
und  schmolz  bei  110°;  es  gab  bei  der  Analyse  Werthe,  welche 
auf  die  Formel:  — 


stimmen:  — 

Berechnet:  Gefunden: 

C  57.31  57.34  pCt. 

H  3.58                    3.61     " 

N  8.35                    8.46    " 

Cl  21.19  21.54    " 

Eine  derartig  zusammengesetzte  Verbindung  wird  ent- 
standen  sein  nach  der  Gleichung:  Ci4Hi4N2  +  2COC12  = 
2HCl+Ci6H12N2O2. 

Stellte    sich    das    Molekularverhaltniss    zwischen    ange- 

1  Vorlaufige  Mittheilung.  Berichte  d.  deutsch.  chem.  Gesellsch.  [hereafter  desig- 
nated as  Berichte]  18,  2427  (1885).  Aus  dem  Berl.  Univ.-Laborat.  No.  ocn.  Ein- 
gegangen  am  15.  August. 


170  MORRIS  LOEB 

wandter  Base  und  Phosgen  auf  4 : 1,  so  wurden  chlorfreie,  bei 
115.5°  schmelzende,  derbe  Nadeln  oder  facherformig  ange- 
ordnete  Blattchen  aus  Alkohol  erhalten,  deren  Analyse  auf 
einen  Harnstoff  der  Formel  CO.  (Ci4Hi3N2)2  deutet. 

Mit  der  genaueren  Untersuchung  der  genannten  Produkte, 
sowie  mit  den  Studium  der  Einwirkung  des  Phosgens  auf 
Guanidine  und  Urethane  bin  ich  noch  beschaftigt. 


UEBER  AMIDINDERIVATE  l 

VOR  einiger  Zeit 2  habe  ich  iiber  einen  Kb'rper  berichtet, 
welcher  durch  Einwirkung  uberschussigen  Phosgens  auf 
das  Aethenyldiphenyldiamin  entsteht,  und  welchem  ich, 
auf  Analysen  gestiitzt,  die  Formel  — 


zuschrieb. 
.N(C6H5) .  COC1 

Ich  habe  seitdem  diese  Annahme  durch  Darstellung  eines 
entsprechenden  Esters  bestatigen  konnen;  zur  Bildung  an- 
derer  Derivate  [234 1]  war  bei  der  Bestandigkeit  jenes  Korpers 
leider  nicht  zu  gelangen.  Schon  bei  der  Darstellung  und 
Reinigung  des  Chlorides  ist  es  geboten,  eine  Temperatur  von 
60°  nicht  zu  ubersteigen,  wenn  man  eine  Ausbeute,  die  bei 
niedriger  Temperatur  60  pCt.  betragen  kann,  nicht  erheblich 
verringern  will. 

Von  kochendem  Wasser  wird  das  Chlorid  nicht  angegriffen, 
von  Sauren  und  Alkalien  dagegen  in  das  Amidin  zuriickver- 
wandelt;  mit  siedenem  Alkohol  liefert  es  Carbanilid,  Essig- 
ester  und  Chloraethyl. 

C16H12N2C12O2  +  3  C2H5OH= 

Bei  der  Darstellung  eines  Esters  muss  jede  Erwarmung 
vermieden  werden.  Natrium  (2  Atome)  wurde  in  Aethylal- 
kohol  gelost,  und  nach  dem  Erkalten  die  alkoholische  Losung 
des  Chlorides  (1  Molekiil)  allmahlich  unter  Abkiihlung 
hinzugesetzt.  Von  dem  sich  sofort  abscheidenden  Kochsalz 

1  Aus  dem  Berl.  Univ.-Laborat.   No.  DCLII,  Berichte,  19,  2340  (1886).    Ein- 
gegangen  am  14.  August. 

2  Berichte,  18,  2427  (1885)  (page  169  of  this  book). 


172  MORRIS  LOEB 

abfiltrirt  und  Uber  Schwefelsaure  im  luftleerem  Raume 
verdunstet,  hinterliess  die  Fliissigkeit  eine  chlorfreie  Sub- 
stanz,  welche  nach  zweimaligem  Umkrystallisiren  aus 
Aether  harte,  glanzende,  rhombische  Krystalle  bildet,  die  bei 
90.5°  schmelzen.  In  alkoholischer  Losung  ist  sie  auch  in  der 
Kalte  wenig  bestandig.  Sie  besitzt  die  Formel 

C2H5O.CO.N—  C  =  :  = 


C2oH22N2O4      Verlangt:  Gefunden: 

I  II  III 

C     67.79  67.74  pCt. 

H      6.21  6.84 

N      7.91  8.51      8.60     '" 

Derselbe,  oder  ein  ahnlicher  Korper  stand  bei  der  Behand- 
lung  des  Amidins  mit  ChlorkohlensaureSthylester  zu  erwar- 
ten.  Eine  Einwirkung  findet  jedoch  erst  bei  60°  statt;  nach 
Verdunsten  der  vom  salzsauren  Amidin  befreiten  Fliissig- 
keit verbleibt  eine  halbfeste  Masse,  welche  an  Aether  kleine 
Mengen  eines  nicht  krystallisirenden  Oeles  abgiebt,  und  im 
Uebrigen  aus  Carbanilid  besteht. 

Sowohl  das  Chlorid  als  der  Ester  werden  durch  Erhitzen 
mit  wasserigem  Ammoniak  in  das  Amidin  zuruckgefiihrt. 
Alkoholisches  Ammoniak  wirkt  wie  reiner  Alkohol.  Wird 
das  Chlorid  in  Benzol  gelost,  und  trockenes  Ammoniakgas 
hindurch  geleitet,  so  scheidet  sich  die  theoretische  Menge 
reinen  Salmiaks  aus.  Die  Losung  enhalt  Aethenyldiphenyl- 
diamin.  Die  Umsetzung  muss  also  folgendermaassen  ver- 
lauf  en  sein  :  — 

Ci6H12N2O2Cl2  +  4  NH3=Ci4H14N2  +  2  NH4C1  +  2  HNCO. 

Analog  entstehen  mit  heissem  Anilin  das  Amidin,  salz- 
saures  Anilin  und  Carbanilid.  Da  such  nun  eine  Amidover- 


UEBER  AMIDINDERIVATE  173 

bindung  aus  dem  [2342]  Chlorearbonylderivate  des  Amidins 
nicht  darstellen  liess,  bemiihte  ich  mich  eine  directe  Anlager- 
ung  von  Cyansaure  resp.  Rhodanwasserstoff  an  das  Amidin, 
welche  zu  ahnlichen  Korpern  gefiihrt  hatte,  zu  bewerkstelli- 
gen.  Auch  diese  Versuche  schlugen  fehl,  da  das  Cyanat  des 
Amidins  schon  in  kalter,  wasseriger  Lb'sung  Kohlensa'ure 
und  Ammoniak  abspaltet;  das  Rhodanat,  welches  ein  Harz 
darstellt,  ist  zwar  bestandiger,  lagert  sich  jedoch  nicht  in 
den  Thioharnstoff  um,  sondern  verwandelt  sich  oberhalb 
100°  in  ein  ubelriechendes  Oel. 

Aethenylimidobenzanilid.  Wird  das  oft  erwahnte  Chlorid 
iiber  seinen  Schmelzpunkt  erhitzt,  so  tritt  bei  150°  eine 
reichliche  Entwickelung  von  Phosgen  ein.  Es  schien  nicht 
unwahrscheinlich,  das  sich  unter  den  Umstanden  der  Korper 


bilden  wiirde. 


Allein  das  stete  Abspalten  von  Phenylcyanat  verhinderte 
mich  denselben  hierbei  zu  isoliren.  Es  ist  mir  aber  gelungen, 
ihn  auf  andere  Weise  darzustellen.  Er  entsteht  namlich, 
wenn  Phosgen  in  Benzol  gelb'st,  auf  einen  Ueberschuss  von 
Aethenyldiphenyldiamin  bei  80°  einwirkt,  oder  wenn  es  als 
Gas  durch  eine  siedende  Chloroformlosung  des  letzteren 
geleitet  wird.  Er  ist  in  Aether,  Alkohol,  Chloroform  und 
Benzol  loslich,  und  krystallisirt  besonders  aus  letztgenanntem 
Losungsmittel  in  grossen  glanzenden  Tafeln  vom  Schmelz- 
punkt 118°. 

Die  Formel  Ci5Hi2N2O  wird  durch  die  Analyse  bestatigt. 


Verlangt: 

Gefunden: 

I 

II 

Ill 

IV 

C    76.27 

77.33 

76.61 

— 

pCt. 

H     5.08 

5.62 

5.60 

— 

« 

N  11.85 

— 

— 

11.73 

12.07  " 

174  MORRIS  LOEB 

Diese  Substanz  ist  identisch  mil  derjenigen,  welche  ich 
friiher1  erwahnt  und  damals  als  bei^l!5.5°  schmelzend  an- 
gefiihrt  habe.  Ueber  den  Schmelzpunkt  erhitzt  braunt  sich 
das  Aethenylimidobenzanilid  bald,  und  entwickelt  etwas 
Isonitril.  Mit  verdiinnter  Salzsaure  gekocht  spaltet  es  sich 
vollkommen,  wobei  Anilin  und  Phenylcyanat  auftreten:  — 

C16Hi2N2O  +  2H2O=C6H5NH2  +  CeHsNCO  +  C2H4O2. 

Versuche  tiber  die  JSinwirkung  von  Phosgen  auf  Benzenyl- 
diphenyldiamin  fiihrten  zu  keinem  Ziele,  da  die  Reaktions- 
producte  allzu  geringe  Krystallisationsfahigkeit  zeigten;  die 
schwierige  Darstellung  und  geringe  Haltbarkeit  der  meisten 
in  der  Literatur  verzeichneten  [2343]  Amidine  hielten  mich 
da  von  ab,  die  nicht  besonders  ergiebige  Untersuchung  auf 
solche  auszudehnen.  Dagegen  habe  ich  aus  dem  Cyananilin 

CeHsNHC  :  NH 

Hof  mann's  2  I  welches  sich  als  Diphenyloxal- 

:  NH 


amidin  auffassen  lasst,  durch  Einwirkung  von  Carbonyl- 
chlorid  einen  krystallinischen  Korper  erhalten,  auf  welchen 
ich  spater  zuriickzukommen  hoffe. 

Ich  mochte  hier  noch  iiber  einen  Versuch  berichten,  Cyan 
an  Aethenyldiphenyldiamin  anzulagern.  Eine  gesattigte 
atherische  Losung  von  Aethenyldiphenyldiamin,  mit  2-3 
Tropfen  Wasser  versetzt,  farbt  sich  beim  Durchleiten  von 
Cyangas  allmahlich  dunkel.  Unterbricht  man  das  Einleiten, 
sobald  die  Fliissigkeit  weinrot  geworden,  und  lasst  sie  unge- 
fahr  16  Stunden  stehen,  so  ist  sie  noch  bedeutend  nach- 
gedunkelt  und  der  Geruch  des  Cyans  demjenigen  der  Blau- 
saure  gewichen.  Zuweilen  haben  sich  auch  schwarze  Krusten 
an  den  Wanden  des  Gefasses  abgesetzt.  Von  diesen  wird 

1  Berichte,  18,  2427  (1885)  (page  169). 

2  Hofrnann,  Liebigs  Annalen,  66,  129  (1848);  73,  182  (1850). 


UEBER  AMIDINDERIVATE  175 

abfiltrirt,  der  Aether  bei  moglichst  niedriger  Temperatur 
verdunstet  und  der  klebrige,  braune  Riickstand  mil  kaltem, 
verdiinnten  Alkohol  vom  farbenden  Harze  befreit.  Das  ver- 
bleibende,  weisse,  krystallinische  Pulver,  welches  zwischen 
Filtrirpapier  moglichst  abgepresst  und  iiber  Schwefelsaure 
getrocknet  wird,  lost  sich  sehr  schwer  in  kaltem  Aether  und 
Benzol.  Es  lasst  sich  nicht  umkrystallisiren,  da  es  beim 
Erhitzen  in  Losungsmitteln  rasch  verharzt;  mit  Alkohol 
benetzt,  zersetzt  es  sich  sogar  schon  an  der  Luft,  In  reinem 
Zustande  schmilzt  es  unter  Zersetzung  bei  165°,  wird  jedoch 
schon  gegen  120°  violett  und  dann  braun. 

Die  Analyse  ergiebt  Zahlen,  welche  sich  auf  einen  Korper 
Ci6Hi6N4O  beziehen  lassen. 

Verlangt:  Gefunden: 

I  II  III  IV  V 

C    68.57     68.24  68.52     68.6  pCt. 

H     5.71       5.24  5.84       6.21    " 

N  20.00  19.55     20.32 

Diese  Formel  lasst  sich  am  einfachsten  nach  dem  Vorbild 
von  Griess'  Cyancarbimidoamidobenzosaure 1  und  von 
Bladins  Cyanphenylhydrazinderivaten  2  in  folgender  Weise 
deuten:  — 

CH3  .  C  .  N  .  C  .  CN 

II       I        \\          +H2O. 
C6H5  .  N  .  C6H5    NH 

Ich  gedenke  den  Korper  weiter  zu  untersuchen.    [2344] 

Zum  Schlusse  mag  hier  noch  ein  Versuch  Erwahnung 
finden,  welchen  ich  im  Laufe  der  Arbeit  iiber  Phosgen  mit 
Urethan  angestellt.  Urethan  (7  Theile)  und  Phosgen  (1 
Theil)  in  Benzol  gelost,  wurden  im  Rohr  auf  75°  erhitzt. 
Beim  Oeffnen  der  Rohren  entwich  viel  Salzsaure  und  das 
Benzol  enthielt  eine  chlorfreie  Substanz,  welche  beim  Um- 

i  Berichte,  11,  1985  (1878).  8  Berichte,  18,  1544  (1885). 


176  MORRIS  LOEB 

krystallisiren  aus  Alkohol  oder  Chloroform  langsam  den 
Schmelzpunkt  194°  erreichte.  Analysen  und  Umwandlung 
in  Biuret  bewiesen,  dass  Allophansaureathy Jester  vorlag; 
selbiger  kann  entweder  nach  der  Gleichung 

2  NH2COOC2H5  -  NH2CONHCOOC2H5  +C2H5OH 

entstanden  sein,  oder  es  hat  sich  intermediar  Carbonyldiure- 
than  CO(NHCOOC2H6)2  gebildet,  welches  beim  Umkrystal- 
lisiren  zerfallen  ist.  Aehnliche  Versuche  iiber  die  Einwirkung 
des  Phosgens  auf  Alanin  fiihrten  zu  keinem  Resultate. 


DAS  PHOSGEN  UND  SEINE  ABKOMMLINGE 

NEBST  EINIGEN  BEITRAGEN  ZU  DEREN 

KENNTNISS  1 

GESCHICHTLICHES 

SELTEN  hat  sich  wohl  ein  erbitterter  Streit  fiir  die  Chemie 
segensreicher  erwiesen,  als  jener,  welcher  am  Anfang  unseres 
Jahrhunderts  iiber  die  Annahme  der  Unzerlegbarkeit  des 
Chlors  entbrannt  ist.  Es  war  nicht  nur  der  Fortschritt, 
welchen  der  endliche  Sieg  von  Davy's  chloristischer  Theorie 
durch  die  Beseitigung  mancher  hemmender  Hypothesen  mit 
sich  brachte:  auch  in  materieller  Hinsicht  haben  wir  dieser 
Discussion  viel  zu  verdanken.  In  dem  Eifer,  gegen  eben- 
blirtige  Gegner  neue  Argumente  zu  erlangen,  ward  gar 
manche  Thatsache  entdeckt,  die  sonst  wohl  lange  unbekannt 
geblieben  ware,  die  uns  aber  heute  von  erster  Wichtigkeit 
erscheint.  Eines  der  besten  Beispiele  liefert  das  Phosgen, 
dessen  Erkennung  eine  inter essante  Episode  in  jenem  Streite 
bildete. 

Als  Humphry  Davy 2  im  Jahre  1811,  seine  Ansicht  entwick- 
elte,  dass  jenes  Gas,  welches  man  bisher  als  oxydirte  Salz- 
saure  aufgefasst,  ein  einfacher  Korper  sei,  und  ihm  den  Namen, 
"Chlorine"  beilegte,  gait  unter  seinen  Landsleuten  Dr. 
John  Murray,  der  Lieblingsschiiler  Black's,  als  berufenster 
und  eifrigster  Verfechter  der  alteren  Ansicht.  Nachdem 
Ersterer  seiner  besten  Argumente  durch  die  Beweiskraft 
Davy'scher  Experimente  verlustig  gegangen  war,  glaubte  er 

1  Inaugural-Dissertation  zur  Erlangung  der  Doctorwfirde  von  der  Philosophischen 
Facultat  der  Friedrich-Wilhelms-Universitat  zu  Berlin.   15.  Marz,  1887.    [Printed 
by  C.  Berg,  Berlin,  1887.] 

2  H.  Davy,  Bakerian  Lecture,  Phil.  Trans.  1811,  p.  1. 


178  MORRIS  LOEB 

seinerseits  in  einigen  neuen  Beobachtungen  eine  schlagende 
Waffe  gefunden  zu  haben. 

[2]  Er  hatte  Kohlenoxyd  und  Chlor  im  Sonnenlichte  zu- 
sammenstehen  lassen,  und  gab  nun  Ammoniak  hinzu, 
worauf  eine  bedeutende  Volumverminderung  folgte.  Da 
nun  Zusatz  starker  Salpetersaure  zu  der  entstandenen 
Salzlosung  eine  Kohlensaureentwickelung  hervorbrachte, 
f olgerte  Murray,  dass  die  Losung  salzsaures  und  kohlensaures 
Ammoniak  enthalte,  was  dadureh  zu  erklaren  sei,  dass,  die 
"oxydirte  Salzsaure"  zerf alien  und  das  Kohlenoxyd  im 
freigewordenen  Sauerstoff  verbrannt  waren.  Um  dieses 
wichtige  Argument  womoglich  zu  entkraften,  wiederholte 
John  Davy,1  der  seinen  beriihmteren  Bruder  untersttitzte, 
diese  Versuche  und  fand  zu  seiner  Genugthuung,  dass  sich 
Chlor  und  Kohlenoxyd  zu  einem  definirten  Gase  vereinigen, 
das  weder  Salzsaure  noch  Kohlendioxyd  zu  liefern  vermag, 
wenn  nicht  anwesende  Feuchtigkeit  den  nothigen  Wasser- 
stoff  und  Sauerstoff  liefert.  Wenn  dasselbe  mit  trocknem 
Ammoniak  vermischt  werde,  so  enthalte  das  entstehende  Salz 
keine  Kohlensaure,  da  Essigsaure  solche  nicht  daraus  aus- 
treibe.  Nur  beim  Zusatz  starker  Mineralsauren  enstehedurch 
Wasserassimilation  Kohlensaure. 

Diesem  Argumente  war  Murray  nicht  mehr  gewachsen; 
jenes  neue  Gas  aber  nannte  John  Davy,  da  es  unter  der 
Einwirkung  des  Sonnenlichtes  entsteht,  Phosgen  und  be- 
trachtete  es  als  eine  Saure,  welche  vier  Aequivalente  Ammo- 
niak zur  Sattigung  verlange.  Erst  1838  gelangte  Regnault2 
zur  Ueberzeugung,  dass  Ammoniak  und  Phosgen  nicht  ein 
einheitliches  Salz  bilden,  sondern  ein  Gemisch  von  Salmiak 
und  "Carbamide"  Obwohl  letzteres  dieselbe  Zusammen- 

1  John  Davy,  Philosophical  Transactions  of  the  Royal  Society,  1812,  p.  144. 
Nicholson's  Journal  of  Natural  Philosophy  and  Chemistry  (London  und  Edinburgh) 
30,  28.  Die  ganze  Controverse  fand  in  diesem  Journale  statt,  in  den  Banden  27-34. 

2  Regnault,  Ann.  de  Chim.  et  Phys.  69,  180  (1838). 


DAS  PHOSGEN  179 

setzung  mil  Harnstoff  habe,  sei  es  doch  nicht  damit  identisch, 
da  noch  so  concentrirte  Losungen  die  charakteristische 
Fallung  mit  Salpetersaure  nicht  gaben.  Er  schrieb  vielmehr 
dem  "Carbamide"  [3]  die  halbe  Molekularformel  des  Harn- 
stoffes  zu.  Natanson1  jedoch,  der  das  Carbamid  sorgfaltiger 
reinigte,  erhielt  ohne  Miihe  den  salpetersauren  Niederschlag 
der  zur  Identifizirung  der  beiden  Substanzen  noch  fehlte. 
Die  Reaktion  verlauft  also  in  folgender  Weise:  — 


Natanson  schrieb  Regnaults  Unvermogen,  den  besprochenen 
Niederschlag  zu  erhalten,  dem  Umstande  zu,  dass  die  Gase 
nicht  geniigend  getrocknet  waren,  weshalb  ein  so  grosser 
Ueberschuss  an  Salmiak  entstanden,  dass  das  Carbamid 
nur  schwer  davon  befreibar  war.  Thatsachlich  ist  aber  die 
Verunreinigung  auch  noch  darin  zu  suchen,  dass  nach  Bou- 
chardat  2  und  Fenton  3  die  Reaktion  nie  glatt  verlauft,  son- 
dern  als  Nebenprodukte  noch  Guanidin-,  Cyanursaure  und 
Melanurensaure  auftreten.  An  besonderer  Bedeutung 
gewann  aber  Regnaults  Reaktion  durch  Hofmann,4  der  am 
Anilin  zeigte,  dass  sie  auch  auf  die  Amine  ausdehnbar  sei. 

Noch  vor  Regnault  hat  Dumas  sich  mit  dem  Phosgengas 
beschaftigt,  und  zwar  ist  es  seine  wichtige  Reaktion  mit  den 
Alkoholen,  welche  er  1833  5  in  voller  Klarheit  auseinander- 
setzte.  Das  Warum  und  das  Wie  entnehme  ich  der  schonen 
Schilderung,  welche  mein  verehrter  Lehrer  von  Dumas 
Leben  und  Wirken  entworfen  hat.6 

"Der  Analyse  nach  liess  sich  der  Zucker  als  eine  Ver- 

1  Natanson,  Liebigs  Annalen  [hereafter  designated  as  Annalen]  98,  287  (1856). 

2  Bouchardat,  Comptes  Rendus,  69,  962  (1869). 

8  Fenton,  J.  Chem.  Soc.  35,  793  (1879)  .  Der  Auszug  im  Jahresbericht  1879,  ist  darin 
unrichtig,  dass  es  F.  Bouchardats  Erfahrungen  nicht  widerspricht:  dasVorhandensein 
von  Guanidin  bestatigt  er;  nach  den  andern  Nebenprodukten  hat  er  nicht  gesucht. 

4  Hofmann,  Annalen,  67,  267  (1846).  6  Dumas,  Annalen,  10,  277  (1834). 

6  Hofmann.  Nekrolog  auf  Dumas,  Ber.  deutsch.  ch.  Ges.  17  (1884),  Ref.  662  ff. 


180  MORRIS  LOEB 

bindung  von  Alkohol  und  Kohlensaure  auffassen,  und  diese 
[4]  Auffassung  schien  in  der  Spaltung  des  Zuckers  durch  den 
Gahrungsprozess  eine  Bestatigung  zu  finden.  Allerdings  war 
es  nicht  gelungen,  durch  direkte  Vereinigung  von  Alkohol 
und  Kohlensaure  Zucker  zu  erzeugen.  Allein  konnte  man 
hoffen,  dass  sich  diese  Vereinigung  wiirde  bewerkstelligen 
lassen,  wenn  man  dem  Alkohol  die  Kohlensaure  in  condicione 
nascendi  bote.  Diese  Betrachtung  veranlasste  Dumas,  die 
Einwirkung  des  Phosgengases  auf  den  Alkohol  zu  studiren. 

"Er  hoffte  eine  Verbindung  zu  erhalten,  welche,  mit 
Wasser  behandelt,  Salzsaure  und  Kohlensaure  liefern  wiirde 
und,  wenn  letztere  mit  dem  Alkohol  in  Verbindung  blieb, 
Zucker  erzeugen  konnte.  Diese  Hoffnung  ist  allerdings  un- 
erfiillt  gebleiben,  aber  der  Versuch  hat  zur  Entdeckung  des 
Chlorkohlensaure-Aethers  gefiihrt,  welcher  unter  dem  Ein- 
flusse  des  Ammoniaks  in  Urethan  oder  Carbaminsaure- Aether 
iibergeht.  Die  Zusammensetzung,  welche  Dumas  fiir  diese 
beiden  typischen  Verbindungen  feststellte,  ist  die  noch  heute 
anerkannte;  aber  wie  viele  Entdeckungen  sind  seitdem  von 
den  Chemikern  auf  dem  von  ihm  erschlossenen  Gebiete  ge- 
macht  worden,  und  welche  Ernten  verspricht  auch  heute 
noch  die  Bebauung  derselben,  zumal  seit  die  neueste  Schwen- 
kung  der  Farbenindustrie  das  ehedem  nur  schwierig  zugang- 
liche  Phosgengas  verfliissigt  der  Forschung  in  beliebiger 
Menge  zur  Verfiigung  stellt." 

Was  nun,  seit  jenen  frtihen  Tagen,  zur  Kenntniss  des  Phos- 
gens  und  seiner  Abkommlinge  beigetragen  worden,  und  welche 
Ansichten  die  Nachfolger  Davys,  Regnaults  und  Dumas 
geleitet,  das  hoffe  ich  im  Folgenden  geordnet  darzuthun. 

DARSTELLUNG 

Zur  Darstellung  des  Phosgens  im  Grossen  dient  noch 
immer  die  Methode  Davys,  gleiche  Volume  Kohlenoxyd  und 


DAS  PHOSGEN  181 

Chlor  den  Sonnenstrahlen  auszusetzen.  Die  Vereinigung  er- 
folgt  rasch,  und  kann  man,  wenn  man  mit  grossen  Gefassen 
[5]  arbeitet,  das  Gas  durch  Abkiihlung  verfliissigen  und  so 
auffangen,  bei  kleineren  Quantitaten  leitet  man  das  Gas  in 
Losungsmittel  ein.  Una  die  grossen  Glasgefasse  und  die 
Nothwendigkeit  der  Belichtung  zu  vermeiden,  hat  man  auch 
haufig  Hofmann's  Darstellungsmethode 1  vorgezogen,  bei 
der  man  Kohlenoxyd  zur  Chlorirung  Uber  siedendes  Anti- 
monpentachlorid  leitet.  Paterno  2  will  die  directe  Vereini- 
gung des  Kohlenoxyds  mit  Chlor  dadurch  bewirken  dass 
er  die  Gase  uber  Knochenkohle  leitet.  Es  giebt  noch  viele 
Vorschlage,  das  Phosgen  durch  Oxydation  von  Tetrachlor- 
kohlenstoff  3  oder  Chloroform 4,  oder  durch  Wechselwirkung 
derselben  mit  Kohlenoxyd  5  darzustellen.  Da  aber  die  Ent- 
stehung  lastiger  Nebenprodukte  unvermeidlich  ist,  und  auch 
die  angewandten  Substanzen  haufig  von  erschwerender 
Beschaffenheit  sind,  hat  sich  keines  dieser  Verfahren  ein- 
blirgern  konnen. 

Wahrend  diese  Methoden  alle  eine  Synthese  des  Phosgens 
aus  seinen  Bestandtheilen  bedeuten,  sind  einige  noch  aus 
theoretischen  Griinden  bemerkenswerth,  da  sie  in  einem 
Abscheiden  des  Phosgens  aus  komplizirteren  Verbindungen 
bestehen  und  gerade  deshalb  neuerdings  anscheinend  wieder 
hervorgeholt  werden. 

Schon  Berzelius  6  hatte  entdeckt,  dass  durch  Einwirkung 
feuchten  Chlorgases  auf  Schwefelkohlenstoff  eine  Substanz 
entsteht,  die  mit  Schwefelsaure  behandelt  Chlorkohlenoxyd 

1  Hofmann,  Annalen,  70,  139  (1849). 

2  Paterno,  Gazzeta  Chimica  Italiana,  8,  233  (1878). 

3  Gustavson,  Zeitschrift  fur  Chem.  1871,  615.  SchUtzenberger,  Compt.  Rend.  66, 
747  (1868). 

4  Dewar  und  Cranston,  Chem.  News,  20,  174  (1869).    Emmerling  und  Lengyel, 
Berichte,  2,  547  (1869). 

6  SchUtzenberger,  Compt.  Rend.  66,  747  (1868). 
6  Berzelius  und  Marcet,  Gilbert's  Annalen,  48, 161. 


182  MORRIS  LOEB 

abspaltet.  Kolbe  1  verdanken  wir  die  Bestatigung  und  [6] 
nahere  Erklarung  dieser  Reaktion,  die  nach  den  heutigen 
Formeln  folgendermassen  verlauft:  — 

I.  CS2+4Cl2+m2O=CCl3SO2Cl+4HCl 

Trichlonnethyl 
sulfonsaurechlorid 

II.  CC13S02C1+H2O  =  COC12  +  SO2+2HC1 
Noch  leichter  lasst  sich  das  Phosgen  aus  Dichlormethyl- 
sulfonsaurechlorid  abspalten,  indem  dasselbe  sich  an  der 
Luft  oxydirt. 

CHC12SO2C1+O=  COC12+HC1+SO2 

Kolbe  fand  auch  dass  das  trockene  Natriumsalz  der  Tri- 
chloressigsaure  beim  Erhitzen  Phosgen  liefert 

CCl3COONa  =  CO  C12  +  CO  +  NaCl 

Perchlorameisensauremethylester  lasst  sich  als  Polymer 
des  Chlorkohlenoxids  auffassen  und  zerf  allt  auch  beim  Durch- 
streichen  auf  340-350°  erhitzter  Rohren  in  dasselbe2 

CC10.OCC13  =  2COC12. 

Auch  verhalt  sich  der  Ester  Reagentien  gegeniiber  dem 
Phosgen  analog.  Ebenso  scheint  Schiitzenbergers 3  Carbonyl- 
chloroplatinit  PtCl2.CO  mit  Leichtigkeit  in  Platin  und 
Phosgen  zu  zerfallen,  und  konnte  wohl  manchmal  da  niitz- 
lich  sein,  wo  ein  fester  Aggregatzustand  der  Reagentien  wiin- 
schenswerth  erschiene. 

BESCHBEIBUNG 

Wir  kennen  das  Phosgen  als  ein  farbloses  erstickend 
riechendes  und  die  Schleimhaute  heftig  angreifendes  Gas, 
welches  bei  gewohnlichen  Drucke  erst  unter  0°  C.  condensirt 

1  Kolbe,  Annalen,  64,  148  (1845). 

2  Cahours,  Ann.  de  Chim.  et  Phys.  [3],  19,  352  (1847). 
1  Schutzenberger,  Jahresbericht,  1870,  381. 


DAS  PHOSGEN  183 

wird,  obwohl  sein  Siedepunkt  bei  8.2°  liegt.1  Die  Fliissig- 
keit  besitzt  bei  0°  das  specifische  Gewichte  1.432. 

[7]  Es  ist  in  Aether,  Chloroform,  den  flussigen  Kohlen- 
wasserstoffen,  Schwefelkohlenstoff  und  Chlorschwefel,  sowie 
in  den  fliissigen  Metallchloriden,  sehr  leicht  loslich.  Nach 
Berthelots  Beobachtung  2  nimmt  das  Benzol  bei  sinkender 
Temperatur  immer  grossere  Mengen  des  Phosgens  auf, 
bis  beim  Gefrierpunkte  des  Benzols  das  sich  verflussigende 
Phosgen  seinerseits  als  Losungsmittel  fungirt.  Da  diese 
Loslichkeit  von  keiner  chemischen  Wirkung  bedingt  ist  und 
sich  die  beiden  Substanzen  unter  den  meisten  Umstanden 
indifferent  zu  einander  verhalten,  wird  das  Phosgen  vielfach 
in  Benzollosung  angewandt,  besonders  auch  wegen  der 
Moglichkeit  genauen  Abwagens. 

Von  Wasser  wird  Phosgen  in  der  Kalte  langsam,  in  der 
Wa'rme  rasch  zerlegt,  wobei  sich  Salzsaure  und  Kohlendioxid 
bilden  und  viel  Wa'rme  frei  wird.3  Zur  quantitativen  gaso- 
metrischen  Bestimmung  des  Phosgens  hat  Berthelot4  eine 
sehr  charakteristische  Methode  ersonnen,  welche  auf  der  Ver- 
dreifachung  seines  Volums  beim  Einbringen  feuchten  Na- 
triumbicarbonats  beruht 

COCl2+2NaHCO3  -  3CO2+2NaCl+H2O 

1  Vol.  8  Vol. 

Da  das  Phosgengas  so  leicht  aus  Kohlenoxyd  und  Chlor 
entsteht,  ware  es  zu  erwarten,  dass  ohne  allzugrosse  Schwie- 
rigkeit  auch  Jod,  Brom  und  Cyan  zum  Vereinigen  mit  Koh- 
lenoxid  zu  bringen  waren.  Im  Gegentheil  lasst  sich  Brom- 
kohlenoxyd  nur  schwierig  durch  Oxydation  des  Bromof orms 

1  Emmerling  und  Lengyel,  Annalen,  Suppl.  7.  105  (1868-1870). 

2  Berthelot,  Annalen,  166,  228  (1870). 

8  Nach  Berthelot  (Annales  [5]  7, 129)  (1879)  entstehen  bei  der  Reaktion  COC12-H 
H2O+Ag  =  CO2Ag+HClAg,+65600  cal.;  nach  Thomsen  (Berichte,  16,  2619) 
(1873)  57970  cal. 

4  Berthelot,  Annalen,  156,  228. 


184  MORRIS  LOEB 

erhalten1  und  ist  eigentlich  noch  nie  ganz  rein  dargestellt  und 
beschrieben  worden. 

Das  Jodphosgen  hat  man  iiberhaupt  noch  nicht  zu  Stande 
gebracht.2  [Auf  das  Cyankohlenoxyd  ist  schon  vielfach  [8] 
gefahndet  worden,  da  es  nicht  nur  wegen  seiner  Analogic 
mit  dem  Chlorkohlenoxyd,  sondern  auch  als  Nitril  einer  zwei- 
basischen  Ketonsaure  Interesse  geboten  hatte.  Es  sind  wohl 
in  der  Litteratur  verschiedene  Notizen  zu  finden,  welche 
iiber  fehlgeschlagene  Versuche  berichten  und  neue  ankiin- 
digen;3  da  jedoch  iiber  die  letzteren  nie  berichtet  wurde, 
kann  man  wohl  annehmen,  dass  auch  sie  resultatlos  verlaufen 
sind. 

Dagegen  ist  neuerdings  die  Existenzf  ahigkeit  des  Chlorcyan- 

,C\ 

kohlenoxyds  OCX  als  eines  dem  Phosgen  sehr  ahnlichen 

'XCN, 

Gases  ausser  Frage  gestellt.  Indem  Bauer4  im  Laufe  einer 
Untersuchung  chlorirter  Nitrile,  Bromwasserstoffgas  auf 
Dichlormethoxyacetonitril  einwirken  liess,  erhielt  er  neben 
Brommethyl  nur  noch  einen  festen  Korper,  welcher  sich  beim 
Erhitzen  unter  theilweiser  Verkohlung  in  ein  schweres  scharf- 
riechendes  Gas  verwandelte,  dessen  Zersetzungsprodukt  es 
mehr  als  wahrscheinlich  machte,  dass  Chlorcyankohlenoxyd 
vorliege.  Die  Reaktion  hatte  mithin  den  Verlauf  genommen 

CH3O.CC12.CN  +  HBr  -  HO.CC12CN  +  CH3Br. 

Bauer  vermuthet  dass  dieser  Korper  unbestandig  sei 
und  sof ort  die  Zersetzung  in  Salzsaure  und  Chlorcyankohlen- 
oxyd erleide. 

1  Emmerling,  Berichte,  13,  873  (1880). 

2  Cowardins,  Chem.  News,  48,  97  (1883). 

8  So  Carstanjen  und  Schertel,  Journ.  prakt.  Chem.  [2],  4,  49  (1871).  GintI,  ibid., 
362. 
4  Bauer,  Annalen,  229,  187  (1885). 


DAS  PHOSGEN  185 

/CN 
HO.CC12.CN  =  O  :  C<        +  HC1 


Dass  das  Phosgen  vielf  ach  als  Analogon  des  Kohlendioxids 
und  Kohlenoxysulfids  zu  betrachten  ware,  erhellt  sowohl 
aus  seiner  Bildungsweise,  als  aus  den  Thatsachen  dass  manche 
[9]  seiner  Derivate  mit  derselben  Leichtigkeit  aus  letzterem 
erhalten  werden  konnen,  wa'hrend  es  sich  selber  bei  vielen 
Reaktionen  in  ersteres  umwandelt.  Dagegen  ist  schon  friih 
beobachtet  worden,  dass  in  Fallen  wo  man  seine  beiden 
Chloratome  successive  ersetzen  wollte,  das  zweite  Chloratom 
sich  viel  bestandiger  verhielt  als  das  erste.  Durch  blosses 
Zusammenbringen  von  Chlorkohlenoxyd  und  Alkohol  wird 
ein  Chloratom  ausgewechselt  und  es  entsteht  der  Ester  der 
Chlorameisensaure.  Dagegen  ist  erhohte  Temperatur, 
langeres  Stehen  oder  dergleichen  nothig,  um  auch  das  zweite 
Chloratom  zum  Austritt  zu  bewegen.  Um  dies  zu  betonen, 
fasst  man  das  Phosgen  gerne  als  Chlorameisensaurechlorid 
auf:  es  gab  sogar  eine  Zeitlang  ernstliche  Meinungsunter- 
schiede,  da  Manche  sich  die  beiden  Chloratome  in  verschie- 
dener  Weise  im  Molekiil  functionirend  dachten.  Schreiner  1 
glaubte  gar  diese  Verschiedenheit  in  den  Derivaten  wieder 
finden  zu  konnen  und  behauptete,  dass,  wenn  er  aus  Phos- 
gen und  Methylalkohol  bereiteten  Chlorameisensaure-Me- 
thylester  mit  Natrium-Aethylat  behandelte,  das  Produkt 
verschieden  sei  von  dem  gemischten  Ester  aus  Chlorameisen- 
saure- Aethylester  und  Natrium-Methylat.  Eine  griindlichere 
Untersuchung  von  Roese2  erwies  jedoch  diese  Idee  als 
nichtig. 

Die  heutige  Auffassung  der  Zustande  in  Molekiil  macht 
aber  auch  ein  Disput  iiber  diese  Frage  inhaltslos.  Es  wiirde 

1  Schreiner,  Journ.  prakt.  Chem.  [2],  22,  353  (1880). 

2  Roese,  Annalen,  205,  227  (1880). 


186  MORRIS  LOEB 

von  gedankenloser  Gewohnung  an  das  rein  Aeusserliche  der 
graphischen  Formeln  zeugen,  miissten  wir  uns  immer  erst 
klar  machen,  dass  in  den  Saurechloriden  auch  das  Chlor 
direkt  mit  dem  Kohlenstoff  verbunden  ist,  so  dass  kein  Unter- 
schied  besteht  zwischen 

/Cl          Cl 
OC<        und    | 
XC1         COC1 

[10]  Ernstlich  eine  Constitution  anzunehmen 

/Cl 

c< 

XOC1) 

wiirde  uns  zum  zweiwerthigen  Kohlenstoff  fiihren  und  ware 
durch  die  Constitution  von  keinem  der  Derivate  zu  begriin- 
den.  Bleiben  wir  also  bei  der  herkommlichen  Formel  des  Phos- 
gens  und  denken  wir  uns  keine  verschiedene  Bindekraft  des 
Kohlenoxyds  f iir  die  beiden  Chloratome :  alsdann  kb'nnen  wir 
getrost  die  Ursache  der  grosseren  Bestandigkeit  der  Chlor- 
ameisensaureester  darin  suchen,  dass,  nachdem  beim  ersten 
Zusammenstoss  der  Molekiile  ein  Chloratom  durch  die  Alk- 
oxyl-Gruppe  ersetzt  worden,  nunmehr  ein  derartiger  Gleich- 
gewichtszustand  zwischen  den  positiven  und  negativen 
Principien  im  Molekiil  eingetreten  ist,  wie  wir  ihm  sonst 
haufig  begegnen.  Denkt  man  sich  z.  B.  die  Schwefelsaure 
etwa  unsymmetrisch  constituirt,  weil  Benzolsulfonsaure  eine 
bestandige  Verbindung  ist,  und  nicht  bei  der  Darstellung  in 
Sulfobenzid  iibergeht? 

ABKOMMLINGE 

Die  Einwirkung  des  Phosgens  auf  anorganische  Substanzen 
bietet  kein  Interesse:  es  wirkt  entweder  unter  direkter  Ab- 
gabe  seines  Chlors  oder  unter  Austausch  desselben  gegen 


DAS  PHOSGEN  187 

Sauerstoff.  Auch  unter  den  kohlenstoffhaltigen  Korpern 
giebt  es  manche,  auf  die  es  genau  wie  Phosphorpentachlorid 
reagirt.  So  fand  Kempf1  dass  Benzaldehyd  in  Benzalchlorid, 
Aceton  in  Dichloraceton,  Essigsaure  in  Acetylchlorid  ver- 
wandelt  wird.  Neuerdings  soil  aus  letzterer  Reaktion  mit 
gutem  Erfolge  die  technische  Anwendung  gezogen  werden, 
dass  man,  behufs  Bildung  der  Saureanhydride,  Phosgengas 
in  die  erhitzten  Sauren  oder  deren  Salze  leitet.2 

[11] 

I.  CH3COONa+COCl2  =  CH3COCl+CO2+NaCl 
II.  CH3COONa+CH3COCl  =  (CH3CO)2O+NaCl. 

Die  Reaktion  zwischen  Phosgen  und  Aldehyd  war  Gegen- 
stand  eines  merkwiirdigen  Irrthums,  welcher  auf  die  chemische 
Theorie  einigen  Einfluss  haben  musste  und  dessen  Beseitigung 
wir  Kekule  und  Zincke  verdanken.  1858  beschrieb  Harnitz- 
Harnitzky 3  einen  Korper,  "  Chloraceten  "  durch  Einwirkung 
von  Chlorkohlenoxyd  auf  Aldehyddampf  entstanden.  Das- 
selbe  habe  einen  konstanten  Siedepunkt,  sei  bei  gewohnlicher 
Temperatur  fliissig,  bei  0°  krystallinisch  fest.  Analysen  und 
Dampfdichte  Bestimmung  ergaben  die  Formel  C2H3C1, 
welche  jedoch  auch  dem  Vinylchlorid  zukomme,  von  dem 
das  Chloraceten  sehr  verschieden  sei.  Da  die  Constitution 

des  Vinylchlorids  ohne  Zweifel  CH2=CHC1  ist,  musste  das 

ii 

Isomer,  aus  Aldehyd  entstanden,  CH3-C— Cl  sein.  Das 
zweiwerthige  Kohlenstoffatom  erweckte  Interesse.  Friedel,4 
Kraut,5  Stacewitz  6  stellten  den  Korper  nach  Harnitz-Har- 
nitzkys  Angaben  dar  und  machten  Derivate  welche  die 

Kempf,  Journ.  praJd.  Chem.  [2],  1,  402  (1870). 

Hentschel,  Berichte,  17,  1284(1884). 

Harnitz-Harnitzky,  Annalen,  111,  192  (1859). 

Friedel,  Compt.  Rend.  60,  930  (1865).  Ann.  chim.  et  phys.  [4],  16,  403  (1869). 

Kraut,  Annalen,  147,  107  (1868). 

Stacewitz,  Zeitschrift  f.  Chemie  (1869),  321. 


188  MORRIS  LOEB 

Constitution  erharten  sollten.  Indem  sie  aber  Harnitz- 
Harnitzkys  Beschreibung  des  ' 'Chloracetens  "  bestatigt 
fanden,  zweifelten  sie  auch  nicht  an  der  Richtigkeit  seiner 
Analysen  und  Constitutionserklarung.  Kekule  und  Zincke 1 
theilten  jedoch  dieses  Vertrauen  nicht  und  ihre  eingehende 
Untersuchung  ergab  die  Nichtexistenz  des  "  Chloracetens." 
Sie  fanden  dass  die  hierfiir  gehaltene  Substanz  ein  Gemisch 
von  Aldehyd  und  Phosgen  sei,ohne  bestimmte  Zusammensetz- 
ung  und  ohne  Bestandigkeit.  Das  Phosgen  begiinstige  die 
Entstehung  von  Paraldehyd,  habe  aber  sonst  keine  Wirkung. 
Die  aus  "  Chloraceten "  entstandenen  Derivate  leiteten  sie 
theils  selber  vom  unveranderten  Aldehyd  her,  theils  ist  dies 
seither  von  Andern  [12]  geschehen.  Allerdings  wa're  zu  er- 
warten  gewesen,  dass  Aldehyd  nach  Analogic  des  Benzalde- 
hyds,  in  Aethylidenchlorid  iibergegangen  ware 

CH3CHO+COC12  =  CH3CHC12+CO2. 

Dies  glaubt  auch  Eckenroth  2  neuerdings  beobachtet  zu 
haben:  da  jedoch  die  diesbeziigliche  Angabe  nur  in  einer 
kurzen  Erwahnung  der  Thatsache  besteht,  lasst  es  sich  noch 
nicht  erklaren,  warum  das  Aethylidenchlorid  der  genauen 
Forschung  Kekule  und  Zinckes  entgangen  sein  soil. 

Wenden  wir  uns  nun  zu  denjenigen  Synthesen,  in  denen 
mittels  der  Carbonylgruppe  ein  wahrer  Aufbau  stattfmdet, 
so  ist  die  Anzahl  der  Falle  einer  direkten  Anlagerungan 
Kohlenstoff  in  der  Fettreihe  etwas  beschrankt.  Bis  vor  Kur- 
zem  hatten  wir  nur  eine  ungliickliche  Angabe  Harnitz- 
Harnitzkys  3  dass  Kohlenwasserstoffe  und  Phosgen  Saure- 
chloride  lieferten,  welcher  Berthelots  und  dessen  Schiller  4 

1  Kekul^  und  Zincke,  Annalen,  162,  125  (1872). 

2  Eckenroth,  Berichte,  18,  518  (1885).   Anmerkung. 

»  Harnitz-Harnitzky,Com^.  Rend.  68,  748(1864).  ^nn.136, 121  (1865).  Compt. 
Rend.  60,  923  (1865). 

4  Berthelot,  Annalen,  166,  216  (1870).  De  Clermont  et  Fontaine,  Ibid.  226. 
Bull.  Soc.  Chim.  n.  s.  13,  9  (1870). 


DAS  PHOSGEN  189 

genauere  Untersuchungen  alle  Glaubwiirdigkeit  geraubt 
hatten;  sodann  eine  Beobachtung  Butlerows,1  dass  Zink- 
methyl  mit  Phosgen  in  Sonnenlichte  eine  krystallinische 
Verbindung  abgiebt,  welche  mit  Wasser  in  Trimethylcar- 
binol  ubergeht.  Nach  andern  von  Butlerow  ausgefiihrten 
Reaktionen  diirfte  man  sich  wohl  den  Vorgang  in  folgender 
Weise  vorstellen  :  — 

I.  2Zn(CH3)2  +  COC12  =  (CH3)3COZnCH3  +  ZnCl2 
II.  (CH3)  3C.OZnCH3  +  H2O  =  (CH3)  3COH  +  ZnO  +  CH4. 

Nachdem,  man  mehrfach  vergebens  versucht  hatte,  Chlor- 
kohlenoxyd,-  analog  anderen  Saurechloriden,  auf  Natrium- 
acetessigester  einwirken  zu  lassen,  haben  im  vorigen  Jahre 
Conrad  und  Guthzeit  2  unter  Anwendung  des  Kupfersalzes 
des  [13]  Acetessigesters  ein  sehr  gunstiges  Resultat  erzielt. 
Das  Produkt  der  Einwirkung  ist  jedoch  nicht,  wie  erwar- 
tet,  ein  Carbonyldiacetessigester  (Diacetylacetondicarbon- 
saureester)  sondern  dessen  Dehydroverbindung. 

CH3—  CO     CO—  CH3 


c*«  CH 

btatt  /  \       /  \ 

/     \  /     \ 
/      CO       \ 
COOC2H5  COOC2H5 

O 

/\t 

CH3—  C      C—  CH3 

entstand  ii      jL 

/\      /\ 
/    \/'    \ 

/          (^Q          \ 

COOC2H5          COOC2H5 

1  Butlerow,  Berichte,  3,  426  (1870). 

2  Conrad  und  Guthzeit,  Berichte,  19,  190  (1886). 


190  MORRIS  LOEB 

Es  gentigt,  diesen  Korper  mit  Ammoniak  zu  behandeln, 
um  ein  Pyridinderivat  zu  erhalten,  den  Dimethyloxypyridin- 
dicarbonsaure-Aethylester. 

NH 

/  \ 
/*      \ 

CHs  —  C*        C  —  CHs 

ii     ii 

c     c 

s\         s\ 
/    \  /'    \ 
•         CO         • 
COOC2H5  COOC2H5 

Die  Anwendung  eines  primaren  Amines  statt  des  Am- 
moniaks  fiihrt  zum  entsprechenden  Substitutionsprodukt 
dieses  eigenartigen  Korpers.  Jedenfalls  diirfte  diese  Reaktion 
des  Phosgens  noch  bedeutsamer  Variirung  fahig  sein. 

In  der  aromatischen  Reihe  ist  eine  unmittelbare  Ein- 
wirkung  des  Phosgens  auf  einen  Kohlenwasserstoff  nur  von 
[14]  Graebe  und  Liebermann  1  beobachtet  worden.  Es  ent- 
steht  bei  200°  ein  Anthracencarbonsaurechlorid.  Behla  2  hat 
dies  als  7-Derivat  erkannt 


\COC1 

und  auch  gefunden,  dass  bei  hoheren  Temperaturen  77-Chlor- 
anthracencarbonsaurechlorid  und  77-Dichloranthracen  ent- 
stehen. 

Friedel,  Ador  und  Crafts  3  wussten  durch  Vermittelung 
des  Aluminiumchlorids  einen  sofortigen  Eintritt  des  Car- 
bonyls  in  den  Benzolkern  zu  bewerkstelligen,  und  erhielten 

1  Graebe  und  Liebermann,  Berichte,  2,  678  (1869). 

2  Behla,  Berichte,  18,  3169  (1885). 

8  Friedel,  Ador  und  Crafts,  Berichte,  10,  1854  (1877). 


DAS  PHOSGEN  191 

je  nach  der  Dauer  der  Einwirkung  Benzoylchlorid  oder  Ben- 
zophenon, 

I.  C6H6+COCl2=C6H5COCl+HCl 
IT.  C6H5COC1+C6H6=C6H5COC6H5+HC1. 

Dies  Verfahren  ist  allgemein  und  1st  nicht  nur  bei  den 
Homologen  des  Benzols,  sondern  auch  in  der  Thiophenreihe 
angewandt  worden. 

Drittens  liess  Wurtz  l  Natrium  auf  Brombenzol  und  Phos- 
gen  einwirken. 

C6H5Br+COCl2+Na2  =  C6H5COCl+NaBr+NaCl.] 

Wenn  diese  Reaktion  auch  typisch  ist,  so  hat  sie  doch  in 
dieser  Form  nur  einmal  Anwendung  gefunden;  man  zieht 
vor,  das  Phosgen  durch  den  verwandten  Chlorameisensaure- 
Ester  zu  ersetzen. 

Ein  viertes  Beispiel  Synthesen  dieser  Art  wird  sich  spater 
so  viel  besser  besprechen  lassen,  dass  ich  nun  zur  Wirkung 
des  Chlorkohlenoxyds  auf  hydroxylhaltige  Verbindungen 
ubergehe. 

[15]  Wie  schon  angedeutet  worden  ist,  entsteht  beim  Ein- 
leiten  von  Phosgen  in  einen  Alkohol  immer  der  Chlorameisen- 
saureester  (Chlorkohlensaureester) :  wie  zum  Beispiel  bei  An- 
wendung des  Methylalkohols 

CH3OH+COC12  =  Cl.COOCHs+HCl. 

Eine  Ausnahme  bildet  bis  jetzt  nur  das  Glycol,  dessen 
zwei  Hydroxylgruppen  zugleich  in  Reaktion  tretend,  zum 
normalen  Carbonat  ftthren.2  Aus  einem  Chlorameisensaure- 
ester  entsteht  der  neutrale  Kohlensaure-Ester  erst  beim 
langeren  Stehen  oder  Erhitzen  mit  dem  Alkohol  oder  durch 
Einwirkung  des  Natriumalkoholats.  Durch  Anwendung 

1  Wurtz,  Comptes  Rendus,  68,  1298  (1869). 

a  Nemirowsky,  Journ.  prakt.  Chem.  28,  439  (1883). 


192  MORRIS  LOEB 

anderer  als  des  urspriinglichen  Alkohols  kann  man  zu  den 
mannigfaltigsten  gemischten  Estern  gelangen.  Audi  greift 
Wasser  die  Chlorameisensaureester  an,  unter  Bildung  von 
sauren  kohlensauren  Estern,  welche  Alkalien  zu  verbinden 
vermogen.  Ferner  lasst  sich  das  Chloratom  im  Chlorameisen- 
saureester durch  einen  Ammoniak-  oder  Amin-Rest  ersetzen. 
Dumas,  welcher  zuerst  die  Reaktion 

2NH3+C1COOC2H5  =  NH2COOC2H5+NH4C1 

ausfiihrte,1  erkannte  sofort,  dass  der  neue  Korper  zum  Harn- 
stoff  in  derselben  Beziehung  stehe,  wie  Oxamaethan  zum 
Oxamid:  er  wahlte  deshalb  den  Namen  Urethan.  Es  ist  dies 
der  Ester  der  hypothetischen  Carbaminsaure.  Wenn  Amine 
in  dieser  Reaktion  das  Ammoniak  vertreten,  entstehen  natiir- 
lich  Ester  substituirter  Carbaminsauren. 

Es  kann  als  Regel  gelten,  dass  jeder  Korper  welcher  mit 
Phosgen  reagirt,  auch  mit  dem  Chlorameisensaureester  eine 
entsprechende  Verbindung  geben  muss.  Die  leichtere  Hand- 
habung  des  letzteren,  als  einer  hoher  siedenden,  geruchlosen 
und  unschadlichen  Fliissigkeit,hat  ihmauch  zu  einer  grosseren 
Beliebtheit  verholfen,  so  dass  die  Anzahl  seiner  Derivate  fast 
unabsehbar  ist.  Fur  die  Wurtz'sche  und  Friedel  und  Crafts'- 
sche  Reaktionen  mit  Kohlenwasserstoffen,  fiir  die  [16]  Dar- 
stellung  mannigfaltiger  Aminsauren  und  Harnsaurederiva- 
ten  ist  diese  Substanz  unschatzbar. 

Phenole  verbinden  sich  ebenfalls  mit  Phosgen  zu  Chlor- 
ameisensaureestern; 2  es  giebt  aber  das  gewohnliche  Phenol 
schon  sofort  etwas  Phenylcarbonat  und  aus  Resorcin  lasst 
sich  auf  diese  Weise  nur  Resorcincarbonat  darstellen.3  Sehr 
auffallend  ist  es,  dass  Chlorkohlenoxyd  durch  auf  200° 
erhitztes  Phenolnatrium  geleitet,  auch  Salicylsaure  liefern 

1  Dumas,  Ann.  chim.  et  phys.  [2],  64,  226  (1833). 

2  Kempf,  Journ.  prakt.  Chem.  [2],  1,  402  (1870). 
8  Birnbaum  und  Lurie,  Berichte,  14,  1754  (1881). 


DAS  PHOSGEN  193 

kann.1  Zur  Erklarung  der  Reaktion  muss  bemerkt  warden, 
dass  ein  Ueberschuss  an  Natriumhydroxyd  nothwendig  1st 
und  dass  allerdings  das  meiste  Phenol  unverandert  abdestil- 
lirt.  Da  fernerhin  auch  durch  Zusammenschmelzen  von 
Phenylcarbonat  und  Phenolnatrium  Salicylsaure  entstehen 
soil,  kann  man  sich  die  Reaktion  in  zwei  Stadien  zerfallend 
denken,  wovon  das  erstere  die  Bildung  des  Phenylcarbonats 
bewirkt.  Darauf  folgt 

(C6H5O)2CO+C6H6ONa+NaOH== 

/ONa 

C6H4<*  +2C6H5OH 

xCOONa 

Salomon,2  und  neuerdings  Schone,3  haben  gezeigt  dass 
sich  die  Merkaptane  in  ihrem  Verhalten  gegeniiber  Phosgen 
und  Chlorameisensaureester  in  keiner  Weise  von  den  Alko- 
holen  unterscheiden.  Auch  hier  ist  es  bei  der  Darstellung  ge- 
mischter  Ester  gleichgiiltig,  ob  man  das  Phosgen  direkt  auf 
das  Merkaptan  einwirken  lasst  und  Natriumalkoholat  zuf  ugt, 
oder  ob  man  mit  Chlorameisensa'ureester  auf  das  Natrium- 
merkaptid  wirkt. 

An  Zahl  und  Interesse  die  wichtigsten  sind  die  stick- 
stoffhaltigen  Derivate  des  Phosgens.  Wir  haben  schon  ge- 
sehen  [17]  wie  Chlorkohlenoxid  mit  Ammoniak  zusammenge- 
bracht  Harnstoff  liefert;  so  entsteht  auch  mit  Anilin  4  in 
ausserst  hef tiger  Reaktion  das  Carbanilid,  Diphenylharnstoff , 
und  aus  jedem  primaren  Amine  der  entsprechende,  sym- 
metrisch  zweifach-substituirte  Harnstoff. 

Aus  vielen  Beispielen  hat  Michler  5  dagegen  gezeigt,  dass 

1  Deutsche  Patente  29929, 30172,  24151,  siehe  Berichte,  18,  Ref.  12,  40,  90  (1885). 

2  Salomon,  Journ.  pralct.  Chem.  [2],  6,  433  ff.  (1872).    7,  254  (1873). 

3  Schone,  Journ.  pralct.  Chem.  [2],  30,  416  (1884). 

4  Hofmann,  Annalen,  67,  267  (1846). 

6  Michler  et  alii,  Berichte,  12,  1162, 1166  (1879).  8, 1665  (1875).  9,  396  (1876). 
Willm  und  Girard,  Berichte,  9,  449  (1876). 


194  MORRIS  LOEB 

sich  sekundare  Amine  insofern  wie  Alkohole  verhalten,  als 
sie  im  Phosgen  vorerst  nur  ein  Chloratom  ersetzen.  So  erhalt 
er  aus  Diathylamin  (C2H5)2NCOC1  welches  er  Diathylharn- 
stoffchlorid  nennt,  obwohl  die  Bezeichnung  als  Diathyl- 
carbaminsaurechlorid  verstandlicher  ware.  Das  Chlor  kann 
durch  Erhitzen  mit  frischen  Mengen  desselben  oder  eines 
andern  Amines  ersetzt  werden.  Auch  kommt  man  mittels 
Natriumalkoholate  wieder  zu  Urethanen,  in  diesem  Falle 
Estern  der  zweifach  substituirten  Carbaminsauren. 

Tertiare  Basen  der  rein  aliphatischen  Reihen  scheinen  dem 
Phosgen  keinen  Angriffspunkt  zu  bieten:  dagegen  tritt  bei 
den  dialkylirten  Anilinen  die  Carbonylgruppe  in  den  Ben- 
zolrest  ein,  und  zwar  in  die  Parastellung  zur  Amidogruppe. 
Dimethylanilin  1  wird  mit  Phosgen  schon  bei  niederer  Tem- 
peratur  zu  Dimethylparaamidobenzoylchlorid.  Dieses  greift 
bei  hoherer  Temperatur  wiederum  das  uberschiissige  Di- 
methylanilin an,  unter  Bildung  des  Hexamethyltriamido- 
benzoylbenzols.2 

(CH3)2NC6H4CO.C6H3CO.C6H4N(CH3)2 

I 

N(C6H3)2 

Man  diirfte  erwarten  auch  das  tetraalkylirte  Diparaami- 
dobenzophenon  unter  den  Reaktionsprodukten  zu  finden. 
Dies  ist  allerdings  dann  der  Fall,  wenn  das  hierzu  berechnete 
Mengen  verhaltniss  eingehalten  wird.  Im  allgemeinen  fand 
aber  Michler  dasselbe  nicht,  an  seiner  Statt  jedoch  einen 
[18]  blauen  oder  violetten  Farbstoff  3  dessen  sich  seit  1885 
dieTechnik  bemachtigt  hat  und  von  dem  Hofmann4  bewiesen 
hat,  dass  er,  bei  angewandten  Dimethylanilin  das  reine  Hexa- 
methylpararosanilin  reprasentire.  Die  Reaktion  geht  im 

1  Michler,  Berichte,  9,  400  (1876). 

2  Michler  und  Dupertius,  Berichte,  9,  1899  (1876). 
a  Michler,  Berichte,  9,  716  (1876). 

4  Hofmann,  Berichte,  18,  770  (1885). 


DAS  PHOSGEN  195 

Autoklaven  vor  sich,   und  Hofmann  fand  die  folgenden 
Gleichungen  fiir  die  wahrscheinlichsten. 

I.  2C6H5N(CH3)2+COC12  =  [(CH3)2NC6H4]2CO+2HC1. 
II.  [(CH3)2NC6H4]2CO+COC12  = 

[(CH3)2NC6H4]2CC12+C02. 
III.  [(CH3)2NC6H4]2CCl2+C6H5N(CH3)2  = 

[(CH3)2NC6H4]3C.HC1+HC1. 

In  Gegenwart  von  Aluminiumchlorid  lasst  sich  derselbe 
Farbstoff  gewinnen,  wenn  Chlorameisensaureester  das  Phos- 
gen  vertritt;  1  oder  aber,  man  kann  gleich  fertiges  Tetra- 
methyldiamidobenzophenon  mit  tertiaren  Anilin  einschlies- 
sen.2  Es  braucht  in  beiden  Fallen  nur  die  zweite  Gleichung  in 
der  Weise  modifizirt  werden,  dass  das  Aluminiumchlorid  das 
Phosgen  als  Chloriibertrager  vertritt.  Bemerkenswerth  ist 
noch  der  Umstand,  dass  man  auch  aus  Perchlorameisen- 
sauremethylester  den  Farbstoff  gewinnen  will:3  es  ist  dies 
eine  praktische  Erkennung  der  Thatsache,  dass  dieser  Ester 
mit  Phosgen  polymer  und  fiir  derartige  Reaktionen  identisch 
ist. 

Fiir  die  eigenthiimliche  Stellung  der  Imidgruppe  im  Pyr- 
rol ist  charakterisch,  dass  sich  dasselbe  dem  Phosgen  gegen- 
iiber  fast  eben  so  gut  wie  ein  Kohlenwasserstoff  als  wie  ein 
sekundares  Amin  gebahrt.  Ciamician  und  Magnaghi  4  haben 
namlich  gefunden,  das  sich  aus  dem  Pyrrolkalium  neben  dem 
zu  erwartenden  Harnstoffe  (Carbonylpyrrol) 


[19]  auch  das  Dipyrrylketon  bildet,  eine  Reaktion  die  Rath- 
selhaftes  bietet,  aber  doch  nur  in  folgender  Weise  gedeutet 
werden  kann  :  — 

1  Deutsches  Patent  29962,  s.  Berichte,  18,  Ref.  40  (1885). 

2  D.  R.  P.  34463.   Berichte,  19,  Ref.  226  (1886). 

3  D.  R.  P.  34607.   Berichte,  19,  Ref.  278  (1886). 

4  Ciamician  und  Magnaghi,  Berichte,  18,  414  (1885). 


196  MORRIS  LOEB 


I.  2C4H4NK+COC12=  CO'  +  2HC1. 


/C4H3NK 


II.  CO  +  2HC1  =  CO  +2KC1 


Noch  schwieriger  mochte  die  Erklarung  zu  finden  sein, 
warum  bei  den  Amidoximen  das  Phosgen  die  primare  Amin- 
gruppe  nicht  beriihren  soil,  wahrend  es  sofort  die  Nitrol- 
gruppe  angreif  t.  So  entsteht  z.  B.  nach  Falck  *  beim  Benzenyl- 
amidoxim 

NOH  NH2 

ii  I 


nicht  OC<  sondern  OC< 


ii  I 

NOH  NH2 

Bis  jetzt  weiss  man  nur,  dass  sich  diese  Anomalie  auch 
bei  andern  Reaktionen  der  Amidoxime  wiederfindet.  T  Jeden- 
falls  kann  es  sonst  als  Regel  gelten,  dass  da,  wo  die  primare 
Aminogruppe  in  complexeren  Korpern  vorkommt,  sie  immer 
dem  Phosgen  den  gewohnten  Angriffspunkt  bietet. 

Augenscheinlich  in  der  Erwartung,  dass  die  Phosphine 
sich  dem  Phosgen  gegemiber  ebenso  verhalten  wiirden  wie 
die  Amine,  haben  Michaelis  und  Dittler  2  mil  Phenylphos- 
phin  den  Versuch  angestellt.  Es  zeigte  sich  jedoch,  dass 
Phosphor  fiir  das  Chlor  die  starkere  Anziehungskraft  habe 

PH2C6H5+2COC12=PC12C6H5+2CO+2HC1. 

1  Falck,  Berichte,  18,  2471  (1885). 

8  Michaelis  und  Dittler,  Berichte,  12,  339  (1879). 


DAS  PHOSGEN  197 

Da  die  Carbonylgruppe  nur  selten  mil  fiinfwerthigem 
Stickstoff  verbunden  auftritt,  steht  zu  erwarten  dass,  wenn 
[20]  uberhaupt  das  Carbonylchlorid  auf  den  Aminen  ent- 
sprechende  Ammoniumsalze  einwirkt,  dies  nur  bei  hohen 
Temperaturen  und  unter  Dissociation  des  Salzes  geschehen 
werde.  Dass  in  der  That  eine  Einwirkung  unter  solchen 
Umstanden  stattfinden  kann,  hat  Hentschel  in  der  Verfol- 
gung  eines  gliicklichen  Gedankens  bewiesen. 

Hofmann,  der  Entdecker  des  Phenylisocyanats,  sogenannten 
Carbanils,  lehrte  dasselbe  auf  zweierlei  Weisen  darstellen: 
einerseits  durch  trockene  Destination  des  Carbanilids  oder 
Oxalyldiphenylguanidins,1  andererseits  durch  Erhitzen  des 
Phenylcarbaminsaure-Aethylesters  mit  Phosphorsaureanhy- 
drid.2  Letztere  Weise,  die  allein  praktisch  ausfiihrbare,  war 
dennoch  muhselig  und  kostspielig,  so  dass  das  Carbanil  nur 
in  kleinen  Mengen  hergestellt  worden  war.  Hentschel's3 
erfolgreicher  Gedanke  bestand  nun  darin,  dass  er  Phosgen- 
gas  Uber  geschmolzenes  Carbanilid  leitete  — 

/NHC6H5 

OCX'  +COC12  =  2C6H5NCO  +  2HC1. 

*NNHC6H5 

Da  aber  das  Carbanilid  selbst  aus  Anilin  und  Phosgen 
entsteht,  war  es  nur  noch  ein  Schritt  die  Darstellung  des 
Carbanils  direkt  aus  Anilin  und  Phosgen  anzustreben.  Um 
jedoch  zu  verhiiten,  dass  bei  der  Destination  Anilin  mit  dem 
Phenylcyanat  ubergehe  und  dasselbe  in  der  Vorlage  in 
Carbanilid  verwandle,  wandte  er  salzsaures  Anilin  an,  durch 
welches  er  bei  200°  Phosgen  leitete.  Dies  Verfahren  ist  so 
vortheilhaft,  dass  es  eine  fabrikmassige  Darstellung  des  Car- 
banils ermoglicht  hat,  und  auch  zur  Kenntniss  vieler  Isocya- 

1  Hofmann,  Annalen,  73,  9  (1850).    74,  33  (1850). 

2  Hofmann,  Berichte,  3,  655  (1870). 

•  Hentschel,  Berichte,  17, 1284  (1884). 


198  MORRIS  LOEB 

nate  fiihrte,  die  nun  aus  den  entsprechenden  Aminen  in  einer 
Operation  erreicht  werden  konnten.  Die  Gleichung  zeigt, 
dass  in  der  That  eine  Dissociation  des  Salzes  in  der  Reaktion 
begriffen  ist. 

C6H5NH3C1+COC12  =  C6H5NCO+3HC1. 

[21]  Man  wird  'dabei  an  Bouchardat's  Erfahrung  erinnert,1 
der  ja,  beim  Einleiten  von  Ammoniakgas  in  Phosgen,  neben 
Harnstoff  und  Guanidin  auch  Cyanursaure  und  Melanuren- 
saure  fand.  Die  letzteren  beiden  Substanzen  kb'nnen  fiiglich 
als  Derivate  der  Isocyansaure  aufgefasst  werden,  welche  sich 
beim  ersten  Eintreten  des  Ammoniaks  gebildet  hatte. 

NH3+COC12  =  HN  =  CO+2HC1. 

Durch  diese  Reaktionen  werden  die  Isocyansaure  und 
ihre  "Ester"  in  die  Reihen  der  Phosgenderivate  hineinge- 
zogen,  zu  welchem  die  so  nah  verwandten  Urethane  und 
Harnstoff e  schon  langst  gehorten.  Es  wird  daher  eine  kurze 
Uebersicht  Uber  die  theoretischen  Beziehungen,  in  welchen 
sich  diese  Substanzen  zu  einander  und  zum  Phosgen  befinden, 
an  diesem  Orte  von  Nutzen  sein. 

Betrachtet  man,  fiir  den  Augenblick,  das  Phosgen  als 
Chlorid  der  Chlorameisensaure,  so  wird  der  Chlorameisen- 
saureathylester  natlirlich  dasjenige  Substitutionsprodukt 
sein,  in  welchem  das  die  Hydroxylgruppe  ersetzende  Chlor- 
atom  wiederum  durch  die  Aethoxylgruppe  verdrangt  ist.  Das 
Urethan  hingegen  ist  der  Ester,  der  Harnstoff  das  Amid,  der 
Amidoameisensaure  oder  Carbaminsaure.  Michler's  Harn- 
stoff chloride  sind  hier  als  die  Chloride  der  zweif ach  alkylirten 
Carbaminsauren  aufzufiihren.  Doch  giebt  es  nicht  nur 
dialkylirte  Carbaminsaurechloride :  wie  Leuckart2  sehr  rich- 
tig  bemerkt,  kann  man  das  sogenannte  Chlorid  der  Cyan- 

1  Siehe  Seite  3  [p.  179  of  this  vol.].         »  Leuckart,  Berichte,  18,  874  (1885). 


DAS  PHOSGEN 


199 


NH.H 

saure  nach  der  Formel     |  auffassen,  und  1st  sogar  bei 

CO.C1 
dem  von  ihm  beobachteten  Salze  des  Phenylcyanats  nur 

NC6H5.H 
eine  Formel  denkbar     |  .     Wir  batten  in  diesen  wohl- 

CO.C1 

defmirten  Korpern  die  Chloride  der  typischen  und  der  ein- 
fach-substituirten  Carbaminsaure.  Dieselben  sind  jedoch 
nicht  sehr  bestandig,  da  sie  gerne  Salzsaure  [22]  abspalten 
und  das  innere  Anhydrid,  das  Lactam,  der  Sauren  bilden.  Es 
waren  hiermit  die  Isocyansaure  als  Lactam  der  Carbamin- 
saure, das  Carbanil  als  Lactam  der  Phenylcarbaminsaure 
auf  zufassen.  Harnstoffe  und  Urethane  entstehen  daraus 
durch  Anlagerung  von  Aminen  resp.  Alkoholen. 

Folgende  Tabelle  moge  veranschaulichen,  wie  die  haupt- 
sachlichsten  Derivate  des  Phosgens  sich  von  demselben  und 
von  einander  ableiten:  — 


Aus  den  primaren 
Phosgen-Derivaten 

Cl 
COOC2H5 

NH.H 
CO.C1 

NC8H5H 
COC1 

N(CH8)2 
COC1 

entstehen  unter 
Einwirkung  von 
H20 

OH 

COOC2H6 

NH;H:"" 
colour 

NCeH5;S; 
CO    \OH\ 

N(CH3)2 

CO  OH* 

nicht  bekannt 

von  C2H5OH 

OCA 

COOC2H6 

NH2 
COOO,H, 

NC8H5H 
COOC2H, 

N(CH3)2 
CO009H9 

von  NH, 

NH3 
COOC2H5 

NH3 
CO.NH2 

NCflH5H 
CONHt 

N(CH3)2 
CONH2 

etc.  etc. 

Lassen  sich  nun  auch  die  Wurtz'schen,  die  Friedel  und 
Crafts'schen  Reaktionen  des  Phenylkerns  mit  Chlorkohlen- 
oxyd  auf  die  primaren  Derivate  des  letzteren  ausdehnen? 


200  MORRIS  LOEB 

Fiir  die  Chlorameisensaureester  ist  diese  Frage  schon  langst 
in  ausgiebigster  Weise  bejaht  worden.  Leuckart,1  der  zuerst 
die  substituirten  Carbaminsaurechloride  als  solche  aussprach, 
hat  uns  auch  mit  einer  derartigen  Anwendung  derselben 
vertrauter  gemacht. 

[23]  Wenn  eine  Mischung  von  Phenylcyanat  und  Benzol 
mit  Aluminiumchlorid  versetzt  wird,  bildet  sich  Benzanilid, 
und  ebenso  entsteht  aus  Phenylcyanat  mit  den  Homologen 
des  Benzols  iminer  das  Anilid  der  entsprechenden  Saure. 
Da  die  Reaktion  nur  in  Gegenwart  von  Aluminiumchlorid 
stattfinden  will,  bemerkt  Leuckart,  dass  die  einfachste 
Erklarung  in  der  Bildung  des  "salzsauren  Carbanils"  und 
der  darauffolgenden  Einwirkung  dieses  Saurechlorids  nach 
der  Friedel  und  Craf  ts'schen  Reaktion  zu  suchen  sei  :  — 


Leider  fehlen  zur  Zeit  noch  Angaben  liber  das  Verhalten 
der  Michler'schen  disubstituirten  Carbaminsaurechloride  bei 
der  Aluminiumchlorid-Reaktion  ;  ein  obigem  analoges  Ver- 
halten ware  der  beste  Beweis  fur  die  Richtigkeit  der  Leuck- 
art' schen  Annahme.2 

SPEZIELLE  ANWENDUNGEN 

Wenn  auch  im  Vorhergehenden  die  Aufzahlung  der  fiir 
das  Gebahren  des  Phosgens  typischen  Reaktionen  erschopft 
ist,  sind  noch  einige  spezielle  Anwendungen  anzufiihren,  der 
Resultate  wegen,  welche  dabei  erzielt  wurden,  insbesondere 
der  Bildung  von  Korpern  die  zu  den  Saurederivaten  des 
Harnstoffs  gerechnet  werden. 

Die  Saureamide  zeigen  fiir  das  Phosgen  nicht  die  gleiche 

1  Leuckart,  loc.  cit. 

2  Seitdem  ich  obiges  geschrieben,  hat  sich  auch  diese  Liicke  ausgefUllt.  Lellmann 
und  Bonhofer  [Berichte,  19,  3231  (1886)]  haben  das  Diphenylcarbaminsaurechlorid 
in  Gegenwart  von  Aluminiumchlorid  auf  Benzol  einwirken  lassen  und  Diphenyl- 
benzamid  erhalten. 


DAS  PHOSGEN  201 

Reaktionsfahigkeit  wie  die  Amine.  Wenigstens  1st  eine 
hohere  Temperatur  notwendig  und  entstehen  viele  Neben- 
produkte.  Bei  primaren  Amiden  lasst  sich  allerdings  der 
Wasserstoff  der  Amidogruppe  noch  ersetzen:  Schmidt1  hat 
durch  Erhitzen  von  Acetamid  und  von  Benzamid  mit  Phos- 
gen  Diacetyl-  resp.  [24]  Dibenzoyl-Harnstoff  erhalten,  ob- 
wohl  auch  hierbei  Chlorid  und  Nitril  der  Sauren  in  er- 
heblichen  Mengen  auftraten.  Beim  Acetanilid,  hingegen 
scheint  die  Reaction  iiberhaupt  noch  nicht  gelungen  zu 
sein.  Beim  Dimethylbenzamid  findet  der  Austausch  statt  :  2  — 


Solche  Korper  lassen  sich  aber  auf  anderen  Wegen  miihe- 
loser  herstellen. 

Wenn  Harnstoff,  das  Amid  der  zweibasischen  Kohlen- 
saure,  mit  Phosgen  erhitzt  wird,  kann  man  zweierlei  Reak- 
tionen  erwarten: 


/NH  H.   c  /c    HI  NH  .  co  .  NH2 

i.  oc<  !  co    n.  oc<  ! 

\NH  iH     Clj  X|C1    HI  NH  .  CO  .  NH2 

Nach  Schmidt  3  entsteht  beim  zweitagigen  Erhitzen, 
unter  hohem  Druck,  auf  100°,  nur  die  letztere  Verbindung, 
die  er  Carbonyldiharnstoff  nennt.  Ebenso  entsteht  aus 
Phosgen  und  Biuret  bei  60°  das  Carbonyldibiuret.  Erhitzt 
man  letzteres  nochmals  mit  Phosgen  so  erhalt  man  fast  reine 
Cyanursaure,  was  Schmidt  durch  folgendes  Bild  erklart: 

XNH—  CO—  NH—  CO—  NH  iH  Clj 

'X  .....  7 
co—  —  "•"•"  ________  --co 

NH—  CO—  NH—  CO—  NH  |H  Clj 

1  Schmidt,  Journ.  prakt.  Chem.  [2],  6,  35  (1872). 

2  Hallmann,  Berichte,  9,  846  (1876). 

3  Schmidt,  Journ.  prakt.  Chem.  [2],  5,  39  (1872). 


202  'MORRIS  LOEB 

Carbonyldiharnstoff  liefert  mit  Phosgen  bei  170°  nur 
theilweise  Cyanursaure.  Es  entsteht  ein  weisses  Neben- 
produkt,  von  derselben  Zusammensetzung;  ob  es  mit  der 
Cyanursaure  isomer  oder  polymer  1st,  weiss  man  noch  nicht. 
Schmidt  nennt  es  Dicyanursaure. 

Es  ist  zu  bemerken,  dass  diese  Synthesen  der  gewohnlichen 
Cyanursaure  als  gute  Argumente  ftir  die  Iso-Konstitution 
derselben  gelten.  Die  Diskussion  dieser  Konstitutionsfrage 
[25]  gehort  nicht  hierher:  wohl  aber  will  es  mir  scheinen  dass 
diesen  Synthesen  als  Beweismittel  nicht  allzuviel  Werth 
beizulegen  ist.  Erstens  kann  man,  so  lange  ein  unbekanntes 
Isomer  als  Nebenprodukt  auftritt,  nicht  entscheiden,  ob  es 
die  gewohnliche  Cyanursaure  ist,  welche  auf  der  glattesten 
Weise  entsteht.  Zweitens  bedingt  die  Reaktion,  wie  oben 
angegeben,  einen  Zerfall  eines  sehr  ausgedehnten  Moleklils, 
wobei  Umlagerungen  keineswegs  auszuschliessen  sind.  Zu- 
dem  sind  Reaktionen  des  Phosgens  nicht  unbekannt,  in  denen 
eine  solche  Umlagerung  bei  gewohnlicher  Temperatur  frei- 
willig  eintritt.  Ich  habe  dies  selber  einmal  beim  Zusatz  von 
in  Benzol  gelostem  Phosgen  zu  o-Amidophenylmerkaptan 
schon  beobachten  konnen.  Sofort  und  quantitativ  erfolgte 
die  Reaktion  — 

xNH2  /N\ 

C6H4<          +COC12=C6H4<       *)C(OH)+2HC1. 
'XSH  'NSX 

Es  war  also  in  der  Kalte  dieselbe  Wanderung  eines  Wasser- 
stoff atoms  vom  Stickstoff  zum  Sauerstoff  erfolgt,  die  man 
zur  Erklarung  einer  Synthese  der  normalen  Cyanursaure 
mittels  Phosgen  annehmen  miisste. 

Oxamid  mit  Phosgen  erhitzt,  gab  nach  Schmidt  nur 
Carbonyldiharnstoff,  unter  gleichzeitiger  Entwickelung  von 
viel  Kohlenoxid  — 


DAS  PHOSGEN  203 

Basarow  1  hingegen  will  auf  diese  Art  Parabansaure  er- 
halten  haben  — 

CO-NH2  CO-NHx 

|  +COC12=    |  >CO+2HC1. 

CO-NH2  CO-NHX 

Wahrend  Phosgen  auf  Harnstoff  erst  bei  betrachtlicher 
Warme  einwirkt,  geschieht  dies  nach  Will 2  bei  den  Thio- 
harnstoffen  sofort,  obwohl  mit  anderen  Resultaten.  Es 
deuten  [26]  dieselben  sogar  auf  eine  abweichende  Konstitu- 
tion  der  geschwefelten  Harnstoff e  von  den  sauerstoffhaltigen. 
Verschiedene  Umstande  uberzeugten  Will,  dass  die  Reaktion 
beim  Sulf ocarbanilid  den  Verlauf  — 


c<  =s 


\ 


I  >CO 
HC1|X 

nicht  haben  kann,  sondern,  dass  das  Endprodukt  derart  ist, 
dass  man  als  einfache  Erklarung  folgende  Gleichung  anneh- 
men  mochte  — 


C^NC6H5H+COC12=C— NC6H6+2  HC1 


\SH  \     \ 

Sulfocarbanilid  V- CO 

Als  vornehmster  Grund  diente  das  Verhalten  der  Sub- 
stanz  beim  Erhitzen 


C<  +COS 

•*NC6H6 
S— CO 

1  Basarow,  Berichte,  6,  477  (1872). 

2  W.  Will,  Berichte,  14,  1486  (1881). 


204  MORRIS  LOEB 

Ware  die  Formel  symmetrisch,  so  miissten  als  Spaltungs- 
produkte  erwartet  werden 


=s>CO  =  C6H5NCS+C6H5NCO 


Man  wird  sich  erinnern,  dass  auch  andere  Forscher  zur 
Annahme  derselben  Formel  fiir  die  Thioharnstoffe  geleitet 
worden  sind,  wie  Will.1  Die  Untersuchungen  des  Letzteren 
erstreckten  sich  nur  auf  die  substituirten  Korper  dieser  Gruppe. 
Indem  ich  versuchte,  zur  Vervollstandigung  auch  das 
einfache  [27]  Thiocarbamid  zu  ahnlicher  Reaction  zu  bringen, 
fand  ich,  dass  es  selbst  bei  den  hochsten  Temperaturen  die  es 
ertragt,  vom  Phosgen  nicht  beeinflusst  wird. 

Es  existiren  noch  eine  Anzahl  amidahnliche  Substanzen, 
in  denen  der  Sauerstoff  des  Saureradikals  durch  eine  Imid- 
gruppe  ersetzt  ist,  die  Amidine  und  Guanidine.  Von  diesen 
war  bisher  nur  das  Triphenylguanidin  auf  sein  Verhalten  mit 
Chlorkohlenoxyd  gepriift  worden.2  Auf  Veranlassung  des 
Herrn  Professors  A.  W.  Hofmann  habe  ich  mich  bemiiht, 
auch  aus  Amidinen  Phosgenderivate  darzustellen,  und  werde 
ich  im  "Experimentellen  Theil"  iiber  diese  und  andere  da  von 
herriihrende  Versuche  weitlaufiger  reden.  Meinen  Bericht 
iiber  die  Phosgenderivate  wiirde  ich  jedoch,  bei  der  grossen 
Anzahl  derselben  die  im  vorausgehenden  keine  Ermahnung 
finden  konnten,  nicht  fiir  vollstandig  erachten,  ohne  ein  Ver- 
zeichniss  der  mir  bekannten  einschlagigen  Litteratur. 

1  So  Liebermann,  Berichte,  12,  1588  (1879). 
*  Michler  und  Keller,  Berichte,  14,  2181  (1881). 


DAS  PHOSGEN  205 

[28]   LITTERATUR-VERZEICHNISS 
DARSTELLUNG  DBS  PHOSGENS 

Aus  Kohlenoxyd  und  Chlor.  Davy,  Phil.  Trans.  Royal  Society,  1812, 144. 

Willm  und  Wischin,  Zeitschr.f.  Chem.  1868,  5. 

Paternd,  Gaaa.  Chim.  Ital.  8,  233  (1878). 

Goebel,  Berzelius  Jahresberickt,  16,  162. 

Hofmann,  Annalen,  70,  139  (1849). 
Aus  Schwefelkohlenstoff  und  Unterchlorigsaureanhydrid.     Schiitzenber- 

ger,  Berichte,  2,  219  (1869). 
Aus  Schwefelkohlenstoff,  Chlor  und  Schwefelsaure. 

Berzelius,  Lehrbuch  der  Chemie,  Bd.  2. 

Kolbe,  Annalen,  54,  148  (1845). 

Aus  Tetrachlorkohlenstoff.   Schiitzenberger,    Comptes   Rendus,  66,  747; 
(1868).    69,  352  (1869). 

Armstrong,  Berichte,  3,  730  (1870). 

Gustavson,  Zeitschr.f.  Chem.,  1871,  615. 
Aus  Chloroform.    Dewar  und  Cranston,  Chem.  News,  20,  174  (1869). 

Emmerling  und  Lengyel,  Berichte,  2,  547  (1869). 
Aus  Perchlorameisensauremethylester.   Cahours,  Ann.  chim.  et  phys.  [3], 

19,  352  (1847). 
Aus  Trichloressigsaurem  Natrium. 

Kolbe,  Annalen,  64,  150  (1845). 

Henry,  Berichte,  12,  1845  (1879). 

ElGENSCHAFTEN 

Berthelot,  Compt.  Rend.  87,  571  (1878). 
Thomsen,  Berichte,  16,  2619  (1883). 
Berthelot,  Annalen,  166,  228  (1870). 

[29]    REAKTIONEN  MIT  KOHLENWASSERSTOFFEN 
Darstellung  von  Sdurechloriden  und  Ketonen 

Mit  Kohlenwasserstoffen  der  Fettreihen. 

Harnitz-Harnitzky,  Compt.  Rend.  60,  923  (1865). 

Berthelot,  Bull.  Soc.  Chim.  n.  s.  13,  9  (1870). 

De  Clermont  et  Fontaine,  ibid.  seq. 
Mit  Zinkmethyl.    Butlerow,  Berichte,  3,  426  (1870).  Siehe  auch  Butlerow, 

Organische  Chemie,  S.  297. 
Mit  Benzol.  Harnitz-Harnitzky,  Compt.  Rend.  68,  748  (1864). 

Berthelot,  Bull.  Soc.  Chim.  n.  s.  13,  9  (1870). 

Friedel,  Crafts  und  Ador,  Berichte,  10,  1854  (1877). 
Mit  Toluol.  Ador  und  Crafts,  Berichte,  10,  2173  (1877). 
Xylol.  Ador  und  Rilliet,  Berichte,  11,  399  (1878). 

Elbs  und  Olberg,  Berichte,  19,  408  (188C). 


206  MORRIS  LOEB 

Mit  Anthracen.  Graebe  und  Liebermann,  Berichte,  2,  678  (1869). 

Behla.  Berichte,  18,  3169  (1885). 
Mit  Phenanthren.  Ibid. 

Brombenzol.  Wurtz,  C.  R.  68,  1298  (1869). 

Thiophen.  Gattermann,  Berichte,  18,  3013  (1885). 

Pyrrol.  Ciamician  und  Magnaghi,  Berichte,  18,  414  (1885). 

REAKTIONEN  MIT  AI^KOHOLEN  UND  PHENOLEN 
Darstettung  von  Chlorameisensaure-  und  Kohlensaure-Estern 

Mit  Methylalkohol.  Dumas  und  Peligot,  Ann.  chim.  et  phys.  68,  52  (1835). 

Hentschel,  Berichte,  18,  1177  (1885). 
Mit  Aethylalkohol.  Dumas,  Ann.  chim.  et  phys.  64,  226  (1833). 

Propylalkohol.  Roemer,  Berichte,  6,  1101  (1873). 

Isopropylalkohol.  E.  Mylius,  Berichte,  6,  972  (1872). 

Isoamylalkohol.  Medlock,  Quart.  Journ.  Ckem.  Society,  1,  368  (1849). 

Glycol.  Nemirowsky,  Journ.  prakt.  Chem.  28,  439  (1843). 

Glycolchlorhydrin.  Nemirowsky,  Journ.  prakt.  Chem.  31, 173  (1844). 

Glycolsaureester.  Heintz,  Annalen,  154,  257  (1870). 

Milchsaure.  Kempf,  Journ.  prakt.  Chem.  [2],  1,  412  ff.  (1870). 

Epichlorhydrin.  Kempf,  ibid. 

Phenol.  Kempf,  Patent  des  Deutschen  Reiches,  30172.  Berichte,  18,  Ref . 

40.  17  (1885). 
Mit  Kresol.  Kempf. 

Thymol.  Kempf. 

Nitrophenol.  Kempf. 
[30] 
Mit  Eugenol.  Salicylaldehyd.  Lowenberg,  Inaug.-Diss.  Berlin,  1885. 

Resorcin.  Birnbaum  und  Lurie,  Berichte,  14,  1754  (1881). 

Merkaptanen.  Salomon,  Journ.  prakt.  Chem.  [2],  6,  433  8.  (1872). 

7,  254  (1873). 

Schone,  Journ.  prakt.  Chem.  [2],  30,  416  (1884). 
Mit  Thiophenol.  Lowenberg. 

Naphtol,  a,  p.  Lowenberg. 

REAKTIONEN  MIT  ALDEHTDEN  UND  SAUREN 
Chlorirung  derselben 

Mit  Acetaldehyd.  Harnitz-Harnitzky,  Annalen,  111,  192  (1859). 

Friedel,  Compt.  Rend.  60,  930  (1865)  und  Ann.  chim.  et  phys.  [4], 

16,  403  (1869). 

Kraut,  Annalen,  147,  107  (1868). 
Stacewitz,  Zeitschr.  f.  Chem.  1869,  321. 
Kekule  und  Zincke,  Annalen  162,  125  (1872). 
Eckenroth,  Berichte,  18,  518  (1885). 


DAS  PHOSGEN  207 

Mit  Benzaldehyd.  Kempf. 

Aceton.  Wroblewski,  Zeitschr.f.  Chem.  [2],  4,  565. 
Essigsaure.  Kempf. 
V.  Meyer,  Annalen,  156,  271  (1871). 

REAKTIONEN  MIT  PRIMAREN  AMINEN 
Darstellung  symmetrischer  Harnstoffe 

Mit  Ammoniak.  J.  Davy,  Phil.  Trans.  1812.  144. 

Regnault,  Ann.  chim.  et  phys.  69,  180  (1809). 

Natanson,  Annalen,  98,  287  (1856). 

Bouchardat,  Compt.  Rend.  69,  94  (1869). 

Fenton,  Journ.  Chem.  Soc.  35,  793  (1879). 
Mit  Anilin.  Hofmann,  Berichte,  57,  267  (1846). 
Orthotoluidin.  Girard,  Berichte,  6,  444  (1873). 
Amidopropylbenzol.  Francksen,  Berichte,  17,  1224  (1884). 
Amidoisobutylbenzol.  Pahl,  Berichte,  17,  1240  (1884). 
Benzidin.  Michler  und  Zimmermann,  Berichte,  14,  2174  ff.  (1881). 
m-Phenylendiamin.  Michler  und  Zimmermann. 
p-Amidodimethylanilin.  Michler  und  Zimmermann. 
Anisidin.  Miihlhauser,  Berichte,  13,  922  (1880). 
Amidoazobenzol.  Berju,  Berichte,  17,  1400  (1884). 

[31]    REAKTIONEN  MIT  SEKUNDAREN  AMINEN 
Darstellung  von  Carbaminsa'urechloriden  und  Harnstqffen 

Mit  Dimethylanin.  Michler  und  Escherich,  Berichte,  12,  1162  (1879). 
Diathylamin.  Michler,  Berichte,  8,  1665  (1875). 
Methylamilin.  Michler  und  Zimmermann,  Berichte,  12,  1165  (1879). 
Aethylendiphenyldiamin.  Michler  und  Keller,  Berichte,  14, 2181  (1881). 
Diazoamidbenzol          )  «  »    •  »,       ,   n»»o  /-.oo-f\ 

Diazobenzolparatoluid  \  Sarauw'  Benchte'  U>  ****  (1881)' 
Diphenylamin.  Michler,  Berichte,  9,  396  (1876). 
Willm  und  Girard,  Berichte,  9,  449  (1876). 

REAKTIONEN  MIT  TERTIAREN  AMINEN 
Bildung  amidirter  Saurechloride  und  Benzophenone 

Mit  Dimethylanilin.  Michler,  Berichte,  9,  4500,  716  (1876). 

Michler  und  Dupertius,  Berichte,  9,  1899  (1876). 

.Patente,  Berichte,  17  (1884).   Ref.  40,339,  60.    18(1885).  Ref.7. 

Hofmann,  Berichte,  18,  770  (1885). 
Mit  Diathylanilin.  Michler,  Berichte,  8,  1665  (1875). 

Michler  und  Gradmann,  Berichte,  9,  1912  (1876). 


208  MORRIS  LOEB 

REAKTIONEN  MIT  AMMONIUMSALZEN 
Bildung  von  Isocyanaten 

Mit  salzs.  Anilin.  Hentschel,  Berichte,  18,  1178  (1885). 

Methylamin.  Gattermann  und  Schmidt,  Berichte,  20,  118  (1887). 

Aethylamin.  Dieselben. 

m-Phenylendiamin.    Gattermann  und  Wrampelmeyer,  Berichte,  18, 

2604  (1885). 
Mit  Benzidin.  Snape,  Journ.  Chem.  Soc.  49,  255  (1886). 

m-Toluylendiamin.  Snape. 

Phenylhydrazin.  Snape. 

REAKTIONEN  MIT  AMIDEN 
Bildung  von  Ureiden 

Mit  Acetamid.  Schmidt,  Journ.  prakt.  Chem.  [2],  6,  39  ff.  (1872). 

Oxamid.  Schmidt. 

Basarow,  Berichte,  5,  477  (1872). 
Mit  Benzamid.  Schmidt. 
[32J 
Mit  Dimethylbenzamid.  Hallmann,  Berichte,  9,  846  (1876). 

Harnstoff.  Schmidt. 

Biuret.  Schmidt. 

Diphenylharnstoff.  Hentschel,  Berichte,  18,  1284  (1885). 

Diphenylthioharnstoff.  Will,  Berichte,  14,  1486  (1881). 

Ditolythioharnstoff.  Will. 

REAKTIONEN  MIT  ANDEREN  KORPERN 

Mit  Benzenylamidoxim.  Falck,  Berichte,  18,  2471  (1885). 

Aethenyldiphenylamidoxim.  Gross,  ibid.  2483. 

Acetessigester.  Conrad  und  Guthzeit,  Berichte,  19,  19  (1886). 

Buchka,  Ber.  18,  2090  (1885). 
Mit  Propionitril.  Hencke,  Annalen,  106,  285  (1858). 

Phenylphosphin.  Michaelis  und  Dittler,  Berichte,  12,  339  (1879). 

Silicomethan.  Wilm  und  Winschin,  Annalen,  147,  150  (1868). 


[33]    EXPERIMENTELLER  THEIL 

DIE  Versuche  von  Michler  und  Keller  1  iiber  die  Ein- 
wirkung  des  Phosgens  auf  das  symmetrische  Triphenylguani- 
din  haben  zu  keinem  erheblichen  Resultate  gefiihrt,  da  die 
entstehenden  Substanzen  die  Kriterien  der  Reinheit  nicht 
besassen.  Man  muss  sogar  bezweifeln,  dass  der  von  ihnen 
erhaltenen  bei  134°  schmelzenden  Substanz  wirklich  die 
Formel 

/NC6H5N 
C<=NC6H5  >CO 


zukomme,  da  dieselbe  von  Stojentin  2  fiir  seinen  wohldefin- 
irten,  bei  190°  schmelzenden  Korper  in  Anspruch  genommen 
wird,  welchen  er  aus  dem  Guanidin  mittels  des  Aethoxalyl- 
chlorids  erhalten  hat. 

Der  Versuch  sollte  nun  zeigen,  ob  ein  Amidin,  vermoge 
seiner  einfacheren  Bauart,  sich  der  Reaktion  williger  herge- 
ben  wollte.  Naturgemass  fiel  meine  Aufmerksamkeit  zuerst 
dem  Aethenyldiphenyldiamin 


zu,  welches  durch  die  Eigenschaften  der  leichten  Darstellung 
und  ziemlichen  Bestandigkeit  vor  den  meisten  Korpern  dieser 
Klasse  hervorstach. 

Im'Laufe  dieser  Arbeit  habe  ich  die  verschiedenen  Dar- 
stellungsweisen,  die  man  flir  das  Aethenyldiphenyldiamin 
vorgeschlagen  hat,  priifen  konnen,  und  bin  zu  der  Ueberzeu- 

1  Berichte,  14,  2181  (1881).  a  Journ.  prakt.  Chem.  32,  29  (1844). 


210  MORRIS  LOEB 

gung  [34]  gelangt,  dass  diejenige,  welche  A.  W.  Hof  mann1  bei 
der  ersten  Beschreibung  dieser  Substanz  empfohlen  hat,  am 
raschesten  und  sichersten  zum  Ziele  fuhrt,  wenn  auch  die 
Reaktion  einen  ziemlichen  Aufwand  an  Ausgangsmaterial 
erfordert 

14C6H5NH2+3CH3COOH+2PC13= 

+6C6H5NH2HCH- 

2C6H5NH2H3PO3 


Ich  verfuhr  gewohnlich  so,  dass  ich  35  Gramm  Anilin 
und  13  Gramm  Eisessig  in  einem  Kolben  vermischte  und  zu 
der  erkalteten  Losung  nach  und  nach  25  Gramm  Phosphor- 
trichlorid  gab.  Die  Anfangs  heftige  Reaktion  wurde  durch 
Abkiihlen  gedampft.  Alsdann  wurde  der  Kolben,  mit  einem 
Riickflussktihler  versehen,  in  einem  Oelbade  erwarmt,  dessen 
Temperatur  langsam  auf  165°  erhoht  wurde.  Hier  verblieb 
derselbe,  bis  das  Aufhoren  der  Salzsaureentwickelung  das 
Ende  der  Reaktion  anzeigte.  Die  Schmelze  loste  sich  fast 
vollkommen  in  kochendem  Wasser;  beim  Erkalten  krystalli- 
sirten  oft  geringe  Mengen  Acetanilid  aus.  Das  aus  der  fil- 
trirten  Losung  mittelst  Ammoniak  gef  allte  Amidin  brauchte 
zur  Reinigung  nur  noch  einmal  aus  Alkohol  umkrystallisirt 
zu  werden.  Die  Ausbeute  betrug  die  Halfte  des  Gewichts 
des  angewandten  Anilins  und  war  folglich  nach  obiger 
Gleichung  fast  theoretisch. 

ElNWIRKUNG  DES  PHOSGENS  IM  UEBERSCHUSS  AUF 

AETHENYLDIPHENYLDIAMIN 

Zehn  Gramm  der  wohlgetrockneten  und  feingepulverten 
Base  wurden  mit  einem  Ueberschuss  verflussigten  oder  auch 
in  Benzol  gelosten  Phosgens  in  einem  Glasrohre  eingeschlossen 
und  4-5  Stundenlang  im  Wasserbade  erwarmt;  die  Tempera- 

1  A.  W.  Hofmann,  Monataberichte  der  Berliner  Akod.  1865,  249. 


PHOSGEN— EXPERIMENTELLER  THEIL    211 

tur  durfte  60°  nicht  ubersteigen.  Der  Rohreninhalt  hatte 
hierauf  eine  tiefgelbe  Farbe  angenommen  und  bestand  zu 
zwei  Dritteln  aus  salzsaurem  Amidin;  mit  warmem  Benzol 
oder  Aether  Hess  [35]  sich  eine  Substanz  ausziehen,  welche 
beim  Verdunsten  des  Losungsmittels  gewohnlich  als  ein  kle- 
briges,  gelbes  Harz  zuriick  blieb.  Auf  Zusatz  einiger  Tropfen 
kalten,  absoluten  Alkohols  verwandelte  sie  sich  jedoch  in  einen 
Krystallbrei,  aus  welchem  das  Oel  durch  Abpressen  entfernt 
wurde.  Nunmehr  wurden  die  Krystalle,  unter  sorgfaltiger 
Vermeidung  des  Siedens,  aus  verdtinntem  Alkohol  umkry- 
stallisirt,  bis  sie  den  gelben  Stich  verloren  und  bei  110°  kon- 
stant  schmolzen.  Die  Substanz  bildete  alsdann  kleine  farb- 
lose  Nadeln  und  erwies  sich  als  chlorhaltig.  Zur  Analyse 
wurde  sie  noch  mit  Aether  gewaschen  und  bei  110°  getrock- 
net. 

I.  0.3013  Gramm  Substanz  gaben  0.6335  Gramm  CO2 

und  0.0979  Gramm  H2O; 
II.  0.2746  Gramm   Substanz  gaben   20.75  ccm  N,  t  = 

24.25°,  B0=755  mm,  7  =  16.6  mm; 
III.  0.3107  Gramm  Substanz  gaben  0.2705  Gramm  AgCl 

nach  Carius.1 
Diese  Analysen  wiesen  unzweideutig  auf  eine  Formel 


Verlangt  ftir:  Gefunden: 

CieHi2N2Cl2O2  I  II  III 

C  192  57.31     57.34 

H  12   3.58      3.61 

N  28   8.36           8.46 

Cl  71  21.19                21.54 

O  32    9.56 


335  10.000 

1  Die  Chlorsilber-NiederschlSge  wurden  auf  einem  tarirten  Gooch'schen  Platin- 
trichter  gesammelt,  bei  120°  getrocknet,  und  gewogen. 


MORRIS  LOEB 

Es  hatte  also  f  olgende  Reaktion  stattgef  unden  :  - 


Aus  10  Gramm  Amidin  liessen  sich  3  Gramm  des  neuen 
Korpers,  also  60  Procent  der  theoretischen  Menge  gewinnen. 
Der  gute  Ausfall  des  Verf  ahrens  hangt  aber  wesentlich  davon 
ab,  dass  der  Korper  in  Losungsmitteln  keiner  hohen  Tem- 
peratur  [36]  ausgesetzt  werde,  da  seine  Bestandigkeit  nur 
sehr  gering  ist.  Seine  Zersetzbarkeit  trat  auch  storend  zu 
Tage,  als  ich  seine  Konstitution  durch  Darstellung  von  Deri- 
vaten  erforschen  wollte. 

Von  kochendem  Wasser  wird  er  nicht  angegriffen,  von 
Sauren  und  Alkalien  hingegen  in  das  Amidin  zuriickver- 
wandelt.  Beim  Kochen  mit  Alkohol  treten  sofort  Essigester 
und  Chlorathyl  auf;  beim  Erkalten  scheiden  sich  kleine 
Nadeln  in  Menge  aus,  welche  chlorfrei  sind,  bei  234°  schmel- 
zen  und  sich  hierdurch,  sowie  durch  den  beim  Erhitzen 
auftretenden  Carbanilgeruch,  als  Carbanilid  charakterisiren. 
Die  Zersetzung  hat  hier  den  Amidinrest  selber  ergriffen  :  — 

Ci6Hi2N2Cl2O2+3C2H5OH  = 

CO(NHC6H5)2+CH3COOC2H5+2C2H5C1+C02 

Es  wurden  Versuche  gemacht,  die  Chloratome  durch 
Aminogruppen  zu  ersetzen.  Da  sich  weder  wasseriges  noch 
alkoholisches  Ammoniak  bewahrten,  wurde  der  Korper  in 
Benzol  gelost  und  trockenes  Ammoniakgas  hindurchgeleitet. 
Es  schied  sich  unter  Erwarmung  eine  der  Chlormenge  genau 
entsprechende  Quantitat  reinen  Salmiaks  aus.  Die  Losung 
enthielt  aber  bloss  Aethenyldiphenyldiamin,  was  sich  nur 
durch  die  f  olgende  Gleichung  erklaren  lasst:  — 


Analog  entstehen  mit  heissem  Anilin  das  Amidin,  salz- 
saures  Anilin  und  Carbanilid. 


PHOSGEN  —  EXPERIMENTELLER  THEIL    213 

Fur  sich  liber  ihren  Schmelzpunkt  erhitzt,  zersetzt  sich 
die  Substanz  bei  150°  unter  reichlicher  Entwickelung  von 
Phosgengas  und  von  Phenylisocyanat. 

Diese  Thatsache  1st  eine  wesentliche  Stiitze  zur  Annahme 
einer  Konstitution  welche  sonst  noch  durch  das  von  Michler 
entdeckte  Verhalten  der  sekundaren  und  tertiaren  Aniline 
gegen  Phosgen  geboten  erscheint 


N-COC1 


[37]  Erfreulicherweise  habe  ich  diese  Annahme  auch  ferner 
bestatigen  konnen,  durch  Darstellung  eines 

Esters.  Es  muss  hierbei  naturlich  jede  Erwarmung  ver- 
mieden  werden.  Eine  2  Atomen  entsprechende  Menge  Na- 
trium wurde  in  Aethylalkohol  gelost  und  nach  dem  Erkalten 
die  alkoholisehe  Losung  des  Chlorids  [1  Molekiil]  allmahlig 
unter  Abklihlung  hinzugesetzt.  Von  dem  sich  sofort  ab- 
scheidendem  Kochsalz  abfiltrirt  und  iiber  Schwefelsaure  im 
luftleeren  Raume  verdunstet,  hinterliess  die  Pliissigkeit  eine 
chlorfreie  Substanz,  welche  nach  zweimaligem  Umkrystalli- 
siren  aus  Aether  harte,  glanzende,  rhombische  Krystalle 
bildet,  die  bei  90.5°  schmelzen.  Der  Analyse  der  in  vacua 
getrockneten  Substanz  zufolge,  ist  in  der  That  der  Ester 
entstanden. 

C6H5 

/NCOOC2H5 
CH3C< 

:^NC6H4COOC2H5 

I.  0.2965  gr  Substanz  gaben  0.7363  gr  CO2  und  0.1730  gr 
H20. 


214  MORRIS  LOEB 

II.  0.1775  gr  Substanz  gaben  12.7  ccm  N.    t  =  10,° 

B0  =  755.8  mm,  T  =  7.1  mm. 

III.  0.2020  gr  Substanz  gaben  14.4  ccm  N.    t  =  12.5,° 
B0=  772.8  mm,  r  =  8.4  mm. 

Verlangt  fur:  Gefunden: 

C2oH22N2O4  I  II  III 

C    240  67.79  67.74 

H     22        6.21  6.48 

N     28        7.91  8.51        8.60 

O    J54  18.08 

354  99.99 

Selbst  in  der  Kalte  ist  der  Ester  in  alkoholischer  Losung 
unbestandig.  Von  wasserigem  Ammoniak  wird  er,  ebenso 
wie  das  Chlorid,  in  das  Amidin  zuruckverwandelt.  Da  ich 
nun  auf  diesem  Wege  keine  Amidoverbindungen  zu  [38] 
gewinnen  vermochte,  bemtihte  ich  mich  eine  directe  Anlager- 
ung  von  Cyansaure  resp.  Rhodanwasserstoffsaure  an  das 
Amidin,  welche  zu  dem  gesuchten  ahnlichen  Korpern  ge- 
f  iihrt  hatte,  zu  bewerkstelligen.  Auch  diese  Versuche  schlugen 
fehl,  da  das  Cyanat  des  Amidins  schon  in  kalter,  wassriger 
Losung  Kohlensaure  und  Ammoniak  abspaltet;  das  Rhod- 
anat,  welches  ein  Harz  darstellt,  ist  zwar  bestandiger,  lagert 
sich  jedoch  nicht  in  den  Thioharnstoff  um,  sondern  verwan- 
delt  sich  oberhalb  100°  in  ein  Ubelriechendes  Oel. 

Uebrigens  lasst  sich  auch  der  Ester  nicht  direct  aus  dem 
Amidin,  durch  die  sie  sonst  so  bequeme  Anwendung  des 
Chlorameisensaureesters,  gewinnen.  Eine  Einwirkung  des- 
selben  findet  erst  bei  60°  statt;  nach  Verdunsten  der  vom 
salzsauren  Amidin  befreiten  Fliissigkeit  verbleibt  eine  halb- 
feste  Masse,  welche  an  Aether  kleine  Mengen  eines  nicht 
krystallisirenden  Oeles  abgiebt  und  im  Uebrigen  aus  Carb- 
anilid  besteht. 


PHOSGEN—  EXPERIMENTELLER  THEIL    215 

EINWIRKUNG   VON   PHOSGEN  AUF  UBERSCHUSSIGES 
AETHENYLDIPHENYLDIAMIN 

Aethenylimidobenzanilid 

Wenn  man,  statt  auf  oben  angegebener  Weise  zu  verf  ahren, 
Phosgengas  in  eine  siedende  Chloroformlosung  des  Amidins 
einleitet,  so  andert  sich  auch  das  Resultat.  Es  entsteht  eine 
chlorfreie  Verbindung,  welche  ihre  Existenz  dem  Zusammen- 
treten  von  einem  Molekiil  Phosgen  und  einem  Molektil 
Amidin  verdankt. 


Dieselbe  entsteht  daher  auch,  und  zwar  in  glatterer 
Reaktion,  wenn  Phosgen  in  Benzol  gelost  bei  80°  auf  einen 
Ueberschuss  von  Aethenyldiphenyldiamin  einwirkt.  Nach 
einstiindiger  Erhitzung  wird  das  Einschlussrohr  geoffnet,  die 
Fliissigkeit  vom  salzsauren  Amidin  befreit  und  das  Benzol 
verdunstet.  Der  krystallinische  Riickstand  wird  mit  kalter, 
starkverdiinnter  Salzsaure  von  unveranderter  Base  befreit 
und  [39]  umkrystallisirt.  Er  ist  in  Aether,  Alkohol,  Chloro- 
form und  Benzol  loslich  und  krystallisirt  besonders  aus  letzt- 
genanntem  Losungsmittel  in  grossen,  glanzenden  Tafeln 
vom  Schmelzpunkt  118°.  Er  ist  viel  bestandiger  als  das 
chlorhaltige  Derivat. 

Die  Analyse  der  bei  100°  getrockneten  Substanz  ergab 
Zahlen  aus  welchen  die  Formel  Ci5Hi2N2O  berechnet  wurde. 

I.  0.1874  gr  Substanz  gaben  0.5314  gr  CO2  und 

0.0948  gr  H2O. 
II.  0.2031  gr  Substanz  gaben  0.5706  gr  CO2  und 

0.1024  gr  H2O. 

III.  0.1720  gr  Substanz  gaben  17.9  ccm  N,  t=23.3°, 
Bo  =758  mm,  r  =  16.7  mm. 


£16  MORRIS  LOEB 

IV.   0.2263  gr  Substanz  gaben  24  ccm  N,  t =21°,  B0 =757  mm, 
r  =  14.5  mm. 

Verlangt  fiir:  Gefunden: 

C15H12N20  I  II  III  IV 

77.33     76.61 
5.62       5.60 

11.73     12.07 


Es  lasst  diese  Zusammensetzung  nur  eine  Auffassung  zu 

/NC6H5 
CH3C<' 


Dieser  Korper,  den  ich  Aethenylimidobenzanilid  benennen 
will,  diirfte  auch  bei  der  schon  erwahnten  Phosgenabspaltung 
entstehen,  welche  das  Chlorid  beim  Erhitzen  erleidet 

/NC6H4CO  Cl 
CH3C< 

\N  -  |CO  Cl 

C6H5 

Die  stets  zugleich  auftretende  Carbanilentwickelung  ver- 
eitelt  jedoch  seine  Isolirung.  Wird  das  reine  Aethenylimido- 
benzanilid [40]  Uber  seinen  Schmelzpunkt  erhitzt,  so  braunt 
es  sich  bald,  und  entwickelt  etwas  Isonitril.  Mit  verdiinnter 
Salzsaure  gekocht  spaltet  es  sich  vollkommen,  wobei  Anilin 
und  Phenylcyanat  als  Produkte  auftreten. 


Diese  Reaktionen  des  Phosgens  sind  die  ersten  die  mit 
einer  Substanz  ausgefiihrt  worden  sind,  welche  je  einen  sekun- 
daren  und  einen  tertiaren  Anilinrest  enthalt.  Sie  zeigen  die 


PHOSGEN—  EXPERIMENTELLER  THEIL    217 

Gleichwerthigkeit  der  beiden  Michler'schen  Reaktionen  an, 
insofern  als  bei  einer  niedrigen  Temperatur  der  Eintritt  der 
Carbonylgruppe  in  den  Phenylkern  ebenso  rasch  erfolgt  wie 
in  den  Imidorest. 

Andernf  alls  musste  auch  ein  Korper  — 


COC1 

aufgetreten  sein,  der  sich  jedoch  nicht  beobachten  liess. 

Ich  wollte  nunmehr  diese  Reaktion  auch  auf  andere 
Amidine  von  analoger  Constitution  ausdehnen,  und  stellte 
zu  diesem  Zwecke  das  Benzenyldiphenyldiamin  dar.  Wieder- 
um  bewahrte  sich  Hofmann's  Darstellungsweise  am  besten, 
mit  der  Modification,  das  man  fertiges  Benzanilid  und  Anilin 
derEinwirkung  des  Phosphortrichlorids  aussetzt;  dieSchmelze 
konnte  nur  mit  kochender  concentrirter  Salzsaure  ausgezogen 
werden.  Die  Einwirkung  des  Chlorkohlenoxyds  auf  dieses 
Amidin  liess  sich  aber  nicht  verfolgen,  da  die  Reaktions- 
produkte  allzu  geringe  Krystallisationsfahigkeit  zeigten. 

Das  Methenyldiphenyldiamin,  welches  ebenfalls  von 
Hofmann  dargestellt  worden  ist,  ist  wenig  bestandig.  Es 
erschien  daher  angemessen,  das  Propionamidin,  behufs  Prii- 
fung  dieser  Reaktion,  darzustellen  :  da  dieser  Korper  noch 
nicht  bekannt  ist,  habe  ich  ihn  und,  zur  Vervollstandigung 
der  Reihe,  auch  die  homologen  Butenyl-  und  Isobutenyl- 
Amidine  analysiert  und  ihre  Eigenschaften  beobachtet. 

[41]      PROPENYLDIPHENYLDIAMIN 

Zur  Darstellung  wird  genau  wie  beim  Aethenylderivat 
verfahren  und  zwar  werden  wiederum  3  Theile  Anilin,  1 


218  MORRIS  LOEB 

Theil  Propionsaure  und  3  Theile  Phosphortrichlorid  ange- 
wandt.  Die  salzsaure  Losung  lasst  auf  Alkalizusatz  die  Base 
als  belles  Oel  fallen,  welches  nur  langsam  fest  wird.  Dieselbe 
1st  in  Alkohol  und  Aether  noch  loslicher  als  das  Aethenyl- 
amidin,  und  krystallisirt  in  langen  weissen  Nadeln,  die  bei 
105°  schmelzen. 

Behufs  Gewinnung  des  Platindoppelsalzes  wurde  die  Base 
in  starkverdiinnter  Salzsaure  aufgelost  und  mit  Platinchlorid- 
losung  versetzt.  Der  alsbald  erfolgende  gelbe  Niederschlag 
ist  in  Wasser  und  Weingeist  wenig,  in  absolutem  Alkohol 
gar  nicht,  in  starker  Salzsaure  dagegen  sehr  leicht  loslich. 

Er  wurde  aus  salzsaurehaltigem  Alkohol  umkrystallisirt, 
mit  absolutem  Alkohol  gewaschen  und  bei  100°  getrocknet. 
Das  Salz  wurde  so  in  prachtvollen,  scharlachrothen  Prismen 
von  einiger  Grosse  erhalten. 

0.6119  Gramm  Substanz,  im  Tiegel  verbrannt,  hinterliessen 
0.1395  Gramm  Asche. 

Verlangt  fur:  Gef linden: 

(Ci5Hi6N2)2.2HClPtCl4 

Pt  22.64  22.79  Procent 

BUTENYLDIPHENYLDIAMIN 

Dasselbe  entstand  aus  1  Theil  Buttersaure,  5  Theilen 
Anilin  und  3  Theilen  PCls.  Die  Ausbeute  war,  auf  die  Saure 
berechnet,  theoretisch.  Schmelzpunkt  der  in  Nadeln  krystal- 
lisirenden  Base  106.5°. 

Das  Platindoppelsalz  fallt  auf  Zusatz  von  Platinchlorid 
zur  salzsauren  Losung  nach  einiger  Zeit  nieder,  und  hat  als- 
dann  eine  schwachgelbe  Farbe.  Es  ist  in  Alkohol  und  heissem 
Wasser  leicht  loslich.  Aus  ersterem  krystallisirt  es  in  gelb- 
rothen,  aus  letzterem  in  braunrothen  Nadeln,  welche  [42] 
bei  durchscheinendem  Lichte  fast  farblos  erscheinen.  Es 
wurde  bei  100°  getrocknet  und  analysirt. 


PHOSGEN— EXPERIMENTELLER  THEIL    219 

0.5869  Gramm  Substanz,  im  Tiegel  verbrannt,  hinter- 
liessen  0.1298  Gramm  Asche. 

Verlangt  fiir:  Gef undent 

C32H38N4PtCl6 

Pt     21.92  22.12  Procent 


ISOBUTENYLDIPHENYLDIAMIN 

Die  auf  ebendieselbe  Weise  dargestellte  Base  fallt  als 
Oel  aus,  welches  nur  nach  langerem  Kochen  mit  Wasser  fest 
wird.  Sie  1st  in  heissem  und  kaltem  Wasser  unloslich  und 
lasst  sich  mit  Dampf  destilliren.  Die  Krystalle  schmelzen 
bei  79°.  Von  kalter  konzentrirter  oder  heisser  verdiinnter 
Salzsaure  wird  dieses  Amidin  leicht  zersetzt,  unter  Bildung 
des  Isobutenylanilids. 

Platindoppelsalz.  Dasselbe  wird  aus  einer  massig  ver- 
diinnten  Losung  als  gelbes  Krystallpulver  erhalten.  Es  ist 
in  heissem  und  kaltem  Wasser  und  in  heissem  Alkohol  loslich. 

0.5052  gr  bei  100°  getrockneter  Substanz  hinterliessen 
0.1109  gr  Pt. 

Verlangt  fiir:  Gef  linden: 


Pt    21.92  21.95  Procent 

Die  Einwirkung  des  Phosgens  auf  das  Propenyldiphenyl- 
diamin  habe  ich  zwar  versucht  und  einen  krystallisirbaren 
Korper  erhalten.  Derselbe  ist  jedoch  nur  in  kleinen  Quanti- 
taten  erhaltlich  und  sehr  zersetzlich.  Er  wurde  aus  Aether 
umkrystallisirt,  war  jedoch  nicht  frei  von  Chlor  zu  erhalten, 
obwohl  eine  Chlorbestimmung  zeigte  dass  dasselbe  nur  Ver- 
unreinigung  sei.  Eine  bei  76°  schmelzende  Portion  wurde 
analysirt,  ohne  jedoch  Zahlen  zu  geben  aus  welchen  sich  etwas 
deuten  liesse. 

Indem  nun  die  Einwirkung  des  Phosgens  auf  Amidine, 


220  MORRIS  LOEB 

welche  sich  von  Aethenyldiphenylamidin  durch  die  zu  ihrer 
[43]  Bildung  angewandten  Sauren  unterscheiden,  keine 
greifbare  Resultate  geliefert  hatte,  war  es  mogiich  dass  sich 
em  besserer  Erfolg  bei  einem  Aethenylarnidin  erzielen  Hesse, 
in  welchem  an  Stelle  des  Anilins  eine  homologe  Base  getreten 
ist.  Ich  beschloss  daher,  Versuche  mit  Derivaten  des  Para- 
resp.  Orthotoluidins  anzustellen. 

EINWIRKUNG   DES   PHOSGENS  AUF  AETHENYLDI-P-TOLUYL- 

DIAMIN 

Dieses  Amidin  ist  zuerst  von  Hofmann  dargestellt,  jedoch 
von  Bernthsen *  genauer  beschrieben  worden.  Ich  befolgte 
die  Vorschrift  des  Ersteren,  und  erhielt  so  leicht  ein  Produkt 
dessen  Schmelzpunkt  188°  mit  Bernthsen's  Angabe  im  Ein- 
klang  stand.  Je  10  g  des  trocknen  Amidins  wurden  mit  2.8  g 
Carbonylchlorid  in  Benzollosung  3-4  Stunden  lang  im  Ein- 
schlussrohr  auf  60°  erhitzt.  Es  hatten  sich  salzsaures  Amidin 
und  eine  im  Benzol  losliche  Substanz  gebildet,  welche  nach 
freiwilligen  Verdampfen  des  Losungsmittels  als  gelbes  Oel 
zuriickblieb.  Zum  krystallisiren  war  dieselbe  nur  dadurch 
zu  bringen,  dass  man  sie  mit  einigen  Tropfen  eiskaltes  ab- 
soluten  Alkohols  Ubergoss,  worauf  sie  zu  einem  Krystall- 
brei  erstarrte.  Sofort  zwischen  Filtrirpapier  abgepresst  und 
mit  warmem  absoluten  Aether  behandelt,  erwiesen  sich 
jedoch  die  Krystalle  zum  grossen  Theil  als  in  Aether  unlos- 
liches,  bei  254°  schmelzendes  Carbotoluid,  wahrend  ein  kleiner 
Theil  in  Losung  ging.  Durch  Vereinigung  der  Produkte 
mehrerer  Operationen,  und  sorgfaltiges  Umkrystallisiren 
aus  Aether,  gelang  es  mir,  eine  kleine  Menge  einer  konstant 
bei  108°  schmelzenden  Substanz  zu  isoliren,  welche  chlor- 
haltig  war  und  in  gut  ausgebildeten  kurzen  Prismen  kry- 
stallisirte.  Die  Ausbeute  war  jedoch  so  schlecht,  dass  es 

1  Hofmann,  Annalen,  184,  364  (1877). 


PHOSGEN— EXPERIMENTELLER  THEIL    221 

mir  nur  mb'glich  war,  eine  einzige  Chlorbestimmung  auszu- 
f iihren,  deren  Resultat  allerdings  gut  auf  einen  Korper  — 

.;NC7H6COC1 

CH3Cf  stimmt. 

XNHC7H6COC1 

[44]  0.2756  gr  Substanz  gaben  nach  der  Carius'schen 
Methode  0.2241  gr  AgCl. 

Verlangt  fiir:  Ci8H16N2Cl2O2  Gefunden: 

Cl     19.56  20.11  Procent 

Die  Absicht,  auch  mil  dem  Orthoditoluylamidin  Versuche 
anzustellen,  musste  ich  aufgeben,  da  ich  nicht  erwarten 
durfte  eine  krystallisirbare  Substanz  aus  diesem  Ausgangs- 
produkte  zu  erhalten,  welches  selber  einen  sehr  niedrigen 
Schmelzpunkt  besitzt.  Da  dieses  Amidin  jedoch  bisher  noch 
nicht  beschrieben  worden  ist,  gebe  ich  an  dieser  Stelle 
meine  Beobachtungen  wieder. 

AETHENYLDI-OTOLUYLDIAMIN 

Zur  Darstellung  verwandelte  ich  40  gr  Orthotoluidin,  12 
gr  Eisessig  und  25  gr  Phosphortrichlorid.  Nachdem  die 
Schmelze  mit  kochendem  Wasser  ausgezogen  war,  fiel  aus  der 
Losung,  auf  Alkalizusatz,  ein  nichtkrystallisirendes,  farb- 
loses  Oel  aus.  Wasserdampf  trieb  unverandertes  Toluidin 
aus  demselben  aus;  der  Ruckstand  erstarrte  jedoch  erst  nach 
einigen  Tagen,  und  zwar  ohne  Spuren  einer  krystallinischen 
Struktur.  Aus  Alkohol  und  sonstigen  Losungsmitteln  seined 
sich  immer  ein  Oel  aus,  das  alsdann  amorph  erstarrte.  Auch 
salpetersaure,  schwefelsaure,  essigsaure  und  oxalsaure  Salze 
liessen  sich  auf  keine  Weise  krystallinisch  erhalten.  Dagegen 
entstanden  schone  Nadeln  des  salzsauren  Salzes  beim  Ein- 
leiten  von  Chlorwasserstoffgas  in  eine  trockene  atherische 
Losung  der  Base. 


222  MORRIS  LOEB 

Zur  Charakterisirung  der  Substanz  stellte  ich  das  Platin- 
doppelsalz  dar.  Es  ist  dasselbe  ein  gelbes,  in  Wasser  schwer- 
losliches,  Krystallpulver,  welches  sich  beim  Erhitzen  mit 
Wasser  oder  Alkohol  leicht  zersetzt.  Ueber  Schwefelsaure 
und  dann  bei  100°  getrocknet  und  im  Porzellantiegel  ver- 
brannt,  lieferte  es  die  der  Theorie  entsprechende  Menge 
Platin.  0.5818  gr  Substanz  hinterliessen  0.1273  gr  Asche. 

Verlangt  fur:  C32H38N4PtCl6  Gefunden: 

Pt    21.92  21.88  Procent 

[45]  Den  Schmelzpunkt  der  Base  fand  ich  bei  45-47°. 

Ehe  ich  das  Feld  der  Amidine  verliess,  lag  der  Wunsch 
nahe,  den  Versuch  anzustellen,  ob  nicht  noch  eine  andere 
Reaktion,  die  der  Cyananlagerung,  sich  bei  denselben  anwen- 
den  liesse.  Hofmann  hatte  dieselbe  zuerst  beim  Anilin  beob- 
achtet  und  dann  auch  auf  Guanidine  ausgedehnt.1  In  der 
That  ist  sie  auch  auf  das  Aethenyldiphenyldiamin  anwendbar. 

EINWIRKUNG  DES   CYANS  AUF  DAS  AETHENYLAMIDIN 

Eine  gesattigte  atherische  Losung  des  Amidins,  mit  2-3 
Tropfen  Wassers  versetzt,  farbt  sich  beim  Durchleiten  von 
Cyangas  allmahlig  dunkel.  Unterbricht  man  das  Einleiten 
sob  aid  die  Fliissigkeit  weinroth  geworden,  und  lasst  sie  unge- 
fahr  16  Stunden  verschlossen  stehen,  so  ist  sie  noch  bedeutend 
nachgedunkelt  und  der  Geruch  des  Cyans  demjenigen  der 
Blausaure  gewichen.  Zuweilen  haben  setzen  sich  auch 
schwarze  Krusten  an  den  Wanden  des  Gef  asses  ab.  Von  diesen 
wird  abfiltrirt,  der  Aether  bei  moglichst  niedriger  Tempera- 
tur  verdunstet  und  der  klebrige,  braune  Riickstand  mit 
kaltem,  verdiinnten  Alkohol  vom  farbenden  Harze  befreit. 
Das  verbleibende,  weisse,  krystallinische  Pulver,  welches 
zwischen  Filtrirpapier  moglichst  abgepresst  und  iiber 

1  Hofmann,  Annalen,  66,  129  (1848). 


PHOSGEN— EXPERIMENTELLER  THEIL    223 

Schwefelsaure  getrocknet  wird,  lost  sich  sehr  schwer  in  kaltem 
Aether  und  Benzol.  Es  lasst  sich  nicht  umkrystallisiren,  da 
es  beim  Erhitzen  in  Losungsmitteln  rasch  verharzt;  mit 
Alkohol  benetzt,  zersetzt  es  sich  sogar  schon  an  der  Luft. 
In  reinem  Zustande  schmilzt  es  unter  Zersetzung^bei  165°, 
wird  jedoch  schon  gegen  120°  violett  und  dann  braun.  Aus 
5  gr  des  Amidins  lassen  sich  3  gr  des  Produktes  erhalten. 

Aus  der  Elementaranalyse  ergiebt  sich  fiir  den  Korper 
eine  Zusammensetzung  Ci6Hi6N4O. 

I.  0.2169  gr  Substanz  gaben  0.5409  gr  CO2  und 
0.1023  gr  H2O. 

II.  0.2625  gr  Substanz  gaben  0.6596  gr  CO2  und 

0.1380  gr  H2O.   [46] 

III.  0.2060  gr  Substanz  gaben  0.5184  gr  CO2  und 

0.1152  gr  H2O. 

IV.  0.3659  gr  Substanz  gaben  63.75  ccm  N,  t=25°, 

B0 =760.5  mm,  r  =  18.4  mm. 
V.  0.1498  gr  Substanz  gaben  27.2  ccm  N,  t=24°, 
B0  =765.5  mm,  r  =  17.34. 

Berechnet  fflr:  Gefunden: 

Ci6H16N40  I  II  III  IV  V         Mittel 

C    192  68.57  68.00   68.52     68.60                    —      68.37 

H     16  5.71  5.24     5.84       6.21                                5.76 

N     56  20.00  —      19.55     20.32     19.94 

O     16  5.71  —    ,    5.93 

280  99.99 

Da  der  Sauerstoffgehalt  wahrscheinlich,  analog  mehreren 
ahnlichen  Cyanderivaten,  vom  Kry stall wasser  herriihrt,  lasst 
sich  diese  Bruttoformel  auflosen:  — 

C16H16N40=Ci4H14N2.C2N2+H20. 

Es  hat  somit  die  Reaktion  nicht  den  Verlauf  genommen 
welchen  Hof  mann  beobachtet  hat,  die  Anlagerung  eines  Cyan- 


224  MORRIS  LOEB 

molekiils  an  je  zwei  primare  oder  sekundare  Amingruppen. 
Viel  eher  f  olgt  das  Amidin  hierin  der  Amidobenzoesaure,  dass 
sich  ein  ganzes  Cyanmolekiil  an  eine  einzelne  ersetzbaren 
Wasserstoff  enthaltende  Stickstoffgruppe  anlagert.  Da  nach 
Griess  *  aus  der  Amidobenzoesaure  die  Cyancarbimidoamido- 
benzoesaure  entsteht  — 

C6H4COOH 
NH-C=NH 

CN 
so  liesse  sich  der  neue  Korper  nach  demselben  Schema  — 


CH3C-NC6H5+H2O 
C=NH 

CN 

[47]  schreiben  und  kann  ich  diese  als  die  wahrscheinlichste 
Konstitutionsformel  aufstellen. 

Der  Korper  erleidet  beim  Erhitzen  mit  Wasser  unter 
Druck  eine  Umwandlung  in  einen  rothen  Farbstoff,  welcher 
in  Chloroform  loslich,  aber  nicht  krystallisirbar  ist  und  daher 
nicht  weiter  untersucht  wurde.  Zugleich  tritt  ein  starker 
Isonitrilgeruch  auf. 

Mineralsauren  zersetzen  die  Substanz  vollkommen,  so  dass 
Anilin  und  Essigsaure  die  hauptsachlichsten  Produkte  sind. 
Wenn  man  dagegen  das  Ci6Hi6N4O  in  ganz  kleinen  Portionen 
in  siedende  starke  Kalilauge  eintragt,  so  lost  es  sich  darin 
auf,  unter  Abscheidung  von  viel  Anilin.  Nachdem  letzteres 
durch  andauerndes  Kochen  entfernt  ist,  setzen  sich  beim 

1  Griess,  Berichte,  11,  1985  (1878). 


PHOSGEN—  EXPERIMENTELLER  THEIL    225 

Erkalten  flimmernde  Krystallblattchen  ab.  Die  abfiltrirte 
Fliissigkeit  enthalt  Essigsaure,  Kohlensaure,  Oxalsaure  und 
Blausaure;  die  ausgeschiedenen  Krystalle  sind  in  Benzol  und 
Aether  nicht,  in  heissem  Alkohol  nur  sehr  sparsam  loslich, 
leicht  dagegen  in  heisser  und  verdiinnter  Salzsaure.  Auf 
Alkalizusatz  fallt  ein  flockiger  weisser  Niederschlag  aus,  der 
zur  Reinigung  einmal  aus  Alkohol  umkrystallisirt  wird. 
Weisse,  silberglanzende  Blattchen,  die  bei  214°  schmelzen 
und  sich  beim  vorsichtigen  Erhitzen  zwischen  Uhrglasern 
zum  Theil  sublimiren  lassen.  Dies  Alles  gab  dem  Zersetzungs- 
produkt  den  Anschein  als  ware  es  das  Hofmann'sche  Cyan- 
anilin  1 

C6H6NH—  C=NH 

C6H5NH—  C=NH 

und  eine  Analyse  hat  die  Vermuthung  in  der  That  besta'- 
tigt:  0.2076  gr  der  getrockneten  Substanz  gaben  42  ccm  N, 
t=17.5°,  B0=764.7,  r  =  11.6. 

Verlangt  fiir:  Gefunden: 

Ci4H14N4 

N    23.53  23.63  Procent. 

[48]  5  Gramm  Ci6Hi6N4O  haben  1.5  Gramm  Cyananilin 
gelief  ert,  welches  Gewicht  der  Half  te  der  in  ersterem  enthalt- 
enen  Anilinreste  entspricht.  Es  kann  also  nicht  bezweifelt 
werden  dass  der  Einfluss  der  Kalilauge  f  olgender  war  — 

2Ci6H16N4O+2H2O  = 


Wenn  diese  glatte  Spaltung  auch  nicht  als  strenger  Beweis 
fiir  die  oben  aufgestellte  Konstitution  des  Korpers  Ci6HieN4O 
gelten  kann,  so  betrachte  ich  sie  dennoch  als  wesentliche 

1  Hofmann,  Annalen,  66,  129  (1848). 


226  MORRIS  LOEB 

Sttitze  derselben,  da  sie  aus  derselben  ungezwungen  hervor- 
geht. 


CCH3 


// 

; 


0#I#NC6H5 

I      \  / 

INH=C       —       C=NH| 

)       I  1 

CN       -          CN 

Andere  Umwandlungen  mit  dem  Korper  Ci6Hi6N4O  aus- 
zufiihren  1st  mir  nicht  gelungen. 


Ich  habe  nun  noch  einige  andere  Substanzen  der  Ein- 
wirkung  des  Phosgengases  unterworfen  und  glaube,  dass  es 
einigen  Werth  hat  iiber  diese  Versuche  zu  berichten,  wenn 
dieselben  auch  nicht  zur  Auffindung  noch  unbekannter  Deri- 
vate  gefiihrt  haben. 

EINWIRKUNG  DES  PHOSGENS  AUF  URETHAN 

In  der  Hoffnung  zu  einem  Carbonyldiurethan 
CO(NHCOOC2H5)2 

zu  gelangen,  habe  ich  wiederholt  7  Teile  Aethylurethans 
mit  1  Theil  Phosgen,  entweder  verfliissigt  oder  in  Benzol 
gelost,  im  Rohr  auf  75°  erhitzt.  Beim  Oeffnen  der  Rohren 
entwichen  jedesmal  unter  starkem  Drucke  Salzsaure  und 
Chlorathyl,  und  es  verblieb  als  Reaktionsprodukt  eine  [49] 
chlorfreie,  in  kaltem  Wasser  unlosliche  Substanz.  Dieselbe 
musste  wiederholt  aus  Alkohol  oder  Chloroform  umkrystalli- 
sirt  werden,  bis  sie  bei  194°  einen  konstanten  Schmelzpunkt 
erreichte.  Sie  wurde  bei  120°  getrocknet  und  analysirt, 
wobei  es  sich  herausstellte,  dass  die  Formel  nicht  die  erwar- 
tete  sondern  C4HsN2O3  sei. 


PHOSGEN— EXPERIMENTELLER  THEIL    227 

I.  0.2749  gr  Substanz  gaben  0.3703  gr  CO2 

und  0.1549  gr  H2O. 

II.  0.2986  gr  Substanz  gaben  55  ccm  N,  t=24°, 

B0 =759.4  mm,  r  =  17.34  mm. 
III.  0.2105  gr  Substanz  gaben  38  ccm  N,  t  =  19°, 
B0 =764.45  mm,  r= 12.72  mm. 


Berechnet  filr: 

Gefunden 

C4H8N203 

I 

II 

c 

48 

36.36 

36.12 

H 

8 

6.06 

6.12 

N 

28 

21.21 

20.73 

0 

48 

36.36 

III 


20.94 


132     99.99 

Es  hatte  sich  somit  Allophansaureester  gebildet,  der  sich 
auch  noch  dadurch  nachweisen  Hess,  dass  er  sich  durch  Er- 
hitzen  mit  Ammoniaklosung  in  das  Biuret  verwandelte.  Ob 
sich  nun  dieser  Ester  direkt  gebildet  hat,  nach  der  Gleichung 

4NH2COOC2H5+COC12  = 

2NH2CO-NH-COOC2H5+2C2H6C1+CO2+H2O 

oder  ob  das  zuerst  entstandene  Carbonyldiurethan  beim  Um- 
krystallisiren  zerfallt,  vermag  ich  nicht  zu  entscheiden.  Ich 
neige  jedoch  zu  ersterer  Ansicht. 

Versuche  mit  dem  homologen  Alanin  fiihrten  zu  keinem 
Resultat. 

Ferner  ergab  sich  aus  wiederholten  Versuchen  die  Un- 
fahigkeit  des  Phosgen  sich  mit  Carbazol,  Succinimid  oder 
Phthalimid,  oder  deren  Kaliumderivaten  zu  verbinden. 

Auf  Hydrazobenzol  wirkt  Phosgen  wie  eine  Saure:  das- 
selbe  verwandelt  sich  in  Benzidin,  welch*  letzteres,  wie  schon 
[50]  bekannt,  erst  bei  hohen  Temperaturen  von  Chlorkohlen- 
oxyd  angegriffen  wird. 


MORRIS  LOEB 

Auch  mit  Thioharnstoff  wollte  das  Phosgen  nicht  in 
Wechselwirkung  treten,  obwohl  die  Versuche  bei  verschiede- 
nen  Temperaturen  angestellt  wurden.  Selbst  nach  wochen- 
langem  Zusammenstehen  liess  sich  keine  Veranderung  er- 
kennen. 

Orthoamidophenylmerkaptan,  welches  ich  der  Giite  des 
Herrn  Professor  Hofmann  verdankte,  reagirt  sehr  leicht 
mit  Phosgen.  Es  wurde  mit  Benzol  vermischt  und  tropfen- 
weise  mit  Phosgenlosung  versetzt,  bis  kein  salzsaures  Salz 
mehr  ausfiel.  Hierbei  wurde  viel  Hitze  frei.  Das  Benzol 
enthielt  einen  chlorfreien,  sofort  bei  136°  konstant  schmelzen- 
den  Korper,  welcher  unschwer  als  Hofmanns  Oxymethenyl- 
verbindung  zu  erkennen  war. 

CeH/'    X)C(OH) 

Schon  Gronvik1  hatte  aus  dem  Orthoamidophenol  mittels 
Chlorameisensaureesters  den  analogen  Korper  erhalten 

C6H4<;/   X)C(OH) 

Versuche,  das  Phosgen  auch  auf  das  Benzenylamidomer- 
kaptan  einwirken  zu  lassen,  blieben  erfolglos. 

[51]  Die  im  vorstehenden  beschriebenen  Versuche  habe  ich 
im  Juli  1885  im  I.  Chemischen  Laboratorium  der  Universi- 
tat  Berlin  begonnen  und  im  Januar  1887  beschlossen.  Es  ist 
mir  eine  grosse  Freude  an  dieser  Stelle  bezeugen  zu  konnen 
wie  viel  ich  meinen  verehrten  Lehrer,  Herrn  Geheimrath 
Professor  Hofmann,  fiir  seine  lebhafte  Anregung,  Belehrung 
und  UnterstUtzung  schulde  und  mit  welcher  Dankbarkeit 

1  Bull.  Soc.  Chim.  n.  s.  25,  177  (1876). 


PHOSGEN-EXPERIMENTELLERJTHEIL    229 

ich  mich  immer  des  Wohlwollens  erinnern  werde,  das  er  mir 
stets  gezeigt. 

Auch  Herrn  Professor  Gabriel  sage  ich  fiir  viele  freund- 
liche  Rathschlage  meinen  herzlichsten  Dank. 

OPPONENTEN:1 

Die  Herren:  W.  Bowman,  Cand.  phil. 
K.  Auwers,  Dr.  phil. 
A.  Reissert,  Dr.  phil. 

THESEN. 

I. 

Die  vier    Bindungseinheiten    des   Kohlenstoffs    sind   unter   einander 
gleichwerthig. 

n. 

Die  einfach-substituirten  Thioharnstoffe  sind  Derivate  des  Thiohara- 
stoffes. 

III. 

Die  Clausius'sche  Theorie  ist  die  beste  Erklarung  der  elektrolytische 
Vorgange. 

1  In  the  public  examination  for  the  Doctor's  degree,  Morris  Loeb  defended 
the  accompanying  theses  against  the  three  opponents  here  named.        [EDITOR.] 


THE  MOLECULAR  WEIGHT  OF  IODINE  IN  ITS 
SOLUTIONS  x 

IT  is  a  matter  of  everyday  observation  that  iodine  has  the 
property  of  dissolving  with  different  colors  in  different  liquids; 
in  some  it  shows  the  reddish-brown  hues  of  its  solid  and 
liquid  states;  in  others  it  acquires  the  violet  color  so  charac- 
teristic of  its  vapor.  The  inference  seems  very  natural  that 
this  diversity  of  color  must  depend  on  a  different  form  of 
aggregation  of  the  iodine  atoms  within  the  solvent.  Since 
the  molecules  of  solids  and  liquids  appear  to  be  more  com- 
plex than  those  of  gases,  we  might  suppose  that  the  red  solu- 
tions contain  more  complex  molecules  of  iodine  than  do  the 
violet  ones.  This  is,  in  fact,  the  usual  assumption;  but  apart 
from  certain  qualitative  indications,  there  has  been  no  proof 
of  its  truth;  quantitative  evidence  has  not  yet  been  forthcom- 
ing in  support  of  the  hypothesis.  That  I  have  been  fortunate 
in  obtaining  such,  I  owe  to  those  new  [806]  means  of  investi- 
gating the  state  of  dissolved  matter  with  which  the  happy 
generalizations  of  Raoult,  and  the  skillful  mathematical  de- 
ductions of  van't  Hoff,  have  furnished  us.  I  refer  to  the 
phenomena  of  "osmotic  pressure,"  which  can  be  measured 
by  the  depression  of  freezing-point  and  vapor  tension  which 
liquids  experience  when  mingled  with  a  foreign  substance. 
By  the  advice  of  Professor  Ostwald,  I  undertook  to  attack 
the  problem  of  the  molecular  weight  of  iodine  in  its  solutions 
by  the  vapor-tension  method,  and  I  now  give  the  results  of 
the  experiments  carried  out  under  his  direction  at  the  Chem- 
ico-Physical  Laboratory  of  Leipzig  University. 

1  Reprinted  from  the  Journal  of  the  Chemical  Society,  63,  805  (October,  1888). 


MOLECULAR  WEIGHT  OF  IODINE     231 


Two  liquids  at  once  presented  themselves  as  the  appropriate 
solvents,  ether  and  carbon  bisulphide;  they  both  have  a  con- 
siderable vapor  tension,  and  they  may  be  considered  as  typi- 
cal of  the  two  kinds  of  solvents  for  iodine.     For,  whereas 
many  iodine  solutions  show  impure  tints,  that  in  ether  is  of  a 
deep  reddish-brown,  and  that  in  carbon  bisulphide  of  a  pure 
violet.  It  was  not  so  easy  to  find  a  proper 
apparatus,   as   Raoult's   is  quite   inap- 
plicable.  He  operates  in  the  Torricellian 
vacuum,  and  has  merely  to  note  the  com- 
parative heights  of  the  mercury  when 
the  solution  and  the  pure  solvent  are 
introduced   above  it.    In   the  case   of 
iodine,  all  contact  with  mercury  must 
obviously   be   avoided.     After   various 
attempts,  the  following  apparatus  was 
devised,    which    is   an    adaptation    of 
Regnault's  manometer  to  the  [807]  pres- 
ent purpose.    It  consists  of  two  bottles  of 
nearly  equal  capacity,  provided  with  care- 
fully ground,  hollow  glass  stoppers.  To 
these  stoppers,  glass  tubes  are  adapted, 
60  cm.  long,  and  of  about  6  mm.  bore,  which  are  bent  twice 
at  right  angles,  so  that  there  is  an  ascending  limb  and  a  hori- 
zontal piece  of  10  cm.  length  each,  and  a  descending  limb,  40 
cm.  long,  for  each  half  of  the  apparatus.  The  lower  ends  of 
these  two  tubes  are  connected  with  each  other  by  means  of 
a  T-tube,  to  which  they  are  joined  by  short  pieces  of  very 
stout  rubber  tubing;  the  third  end  of  the  T-tube  serves  as  a 
communication  with  the  exterior  when  needed,  and  carries  a 
rubber  tube  with  pinchcock.    The  communication  between 
the  two  halves  of  the  apparatus  can  also  be  interrupted  by 
means  of  a  pinch-cock  on  one  of  the  rubber  joints.   In  one 


MORRIS  LOEB 

of  the  bottles,  the  iodine  solution  is  placed,  whilst  the  pure 
solvent  is  put  into  the  other.  These  liquids  are  contained  in 
glass  tubes,  drawn  out  at  both  ends  into  capillaries  that  make  an 
obtuse  angle  with  the  wider  part.  The  tubes  are  first  weighed, 
then  filled,  closed  before  the  blowpipe,  and  again  weighed. 
They  contain  about  3  cc.  of  liquid,  pass  readily  through  the 
narrow  necks  of  the  bottles,  and  can  be  broken  by  moderately 
shaking  the  bottles.  Before  this  is  done,  however,  the  bottles 
are  closed  with  their  stoppers — smeared  with  deliquesced 
phosphoric  acid  to  insure  a  perfect  joint  —  and  are  placed  in  a 
water-bath  of  constant  temperature.  The  T-tube  is  now  con- 
nected with  a  two-necked  Woulff's  bottle,  filled  with  colored 
distilled  water,  and  communicating  by  its  second  neck  with  an 
air-pump.  Air  is  exhausted,  until  the  pressure  within  the  appa- 
ratus is  diminished  to  an  extent  equivalent  to  the  amount  of 
tension  to  be  expected  from  the  vapors  of  the  liquids,  and 
the  pinch-cock  is  then  closed,  so  as  to  interrupt  communica- 
tion with  the  Woulff  s  bottle.  The  air-pump  being  discon- 
nected, atmospheric  pressure  is  restored  in  the  WoulfFs 
bottle,  and  on  carefully  opening  the  pinch-cock  the  water  is 
allowed  to  ascend  halfway  up  the  long  tubes;  the  pinch-cock 
is  then  closed,  and  the  WoulfFs  bottle  removed.  The  appa- 
ratus is  thus  converted  into  a  very  delicate  differential  mano- 
meter, affording  direct  readings  of  the  difference  of  pressure 
in  the  two  bottles  in  terms  of  water  centimetres;  for  con- 
venience, the  two  tubes  are  brought  closely  together  (see 
figure)  and  a  scale  is  placed  behind  them. 

The  apparatus  is  quite  independent  of  changes  in  the  at- 
mospheric pressure;  the  change  in  capacity,  caused  on  either 
side  by  an  alteration  in  the  level  of  the  water  in  the  tubes,  is, 
moreover,  so  slight  in  proportion  to  the  volume  of  air  in  the 
bottles,  that  it  can  safely  be  neglected;  the  effect  of  capillarity 
in  the  two  tubes  is  equal  and  opposite,  so  that  this  too  may 


MOLECULAR  WEIGHT  OF  IODINE     233 

be  left  out  of  account.  There  remains  only  the  effect  of  the 
air  left  in  the  apparatus  by  the  air-pump.  It  [808]  is  obvious 
that  equilibrium  being  once  established,  and  the  tempera- 
ture in  all  parts  remaining  the  same,  the  pressure  of  the  air 
in  the  one  half  will  always  counterbalance  that  in  the  other. 
In  fact,  partial  exhaustion  was  only  resorted  to  as  a  means  of 
preventing  too  great  an  outward  pressure  during  the  course 
of  the  experiment,  since  it  was  difficult  to  prevent  leakage 
where  there  was  any  outward  pressure  upon  the  stoppers. 
Partial  exhaustion,  besides  obviating  this  difficulty,  proved 
directly  advantageous  by  promoting  a  more  rapid  diffusion 
of  the  vapors,  and  thereby  shortening  the  duration  of  the 
observations. 

The  apparatus  having  been  made  ready,  communication 
between  the  two  halves  was  temporarily  interrupted,  and  the 
tubes  containing  the  liquids  broken  by  shaking  the  two 
bottles  simultaneously.  After  ten  to  fifteen  minutes  communi- 
cation was  restored,  and  now  the  level  of  the  water  in  the  two 
manometer  tubes,  equal  before,  was  seen  to  differ  consider- 
ably, indicating  a  higher  pressure  in  the  bottle  containing  the 
pure  solvent.  Readings  being  made  from  time  to  time,  this 
difference  of  level  sometimes  appeared  virtually  constant  for 
hours,  whilst  in  other  cases  it  would  exhibit  considerable 
variations,  which  I  ascribe  to  slight  inequalities  of  tempera- 
ture and  to  the  unequal  concentration  of  the  solution  in  dif- 
ferent parts  of  its  bottle.  After  standing  twenty-four  hours, 
the  aqueous  vapor  from  the  manometer  tubes  generally  began 
to  diffuse  into  the  bottles,  and  by  moistening  the  ether  or 
carbon  bisulphide  rendered  further  observations  useless. 

The  readings  give  the  difference  between  the  vapor  tension 
of  the  pure  solvent  and  that  of  the  solution;  that  is,  the  de- 
pression of  tension  which  corresponds  with  the  proportion 
of  iodine  to  solvent  in  the  solution.  To  calculate  the  con- 


234  MORRIS  LOEB 

centration  of  the  solution  at  the  moment  of  observation,  I  re- 
quired two  data:  the  amount  of  iodine  and  of  solvent  intro- 
duced into  the  bottle  (which  I  obtained  from  the  weighings 
of  the  sealed  tubes  and  from  the  known  strength  of  the  solu- 
tion with  which  they  were  filled) ;  and  secondly,  the  amount 
of  solvent  which  had  assumed  the  gaseous  state,  and  must 
therefore  be  deducted  from  the  original  quantity  in  solution. 
This  was  easily  calculated  by  the  regular  gasometric  formula, 
the  volume  of  gas  being  270  cc.,  the  temperature  being  known, 
and  the  pressure  being  that  of  the  vapor  of  the  pure  solvent, 
less  the  depression  formed  by  the  direct  observation.  I  found 
that  I  could  employ  the  vapor  tensions  of  pure  ether  and  car- 
bon bisulphide  from  tables  calculated  from  Regnault's  meas- 
urements, as  a  few  direct  comparisons  proved  that  they  agreed 
with  those  given  by  my  apparatus,  within  the  limits  of  ex- 
perimental error.  The  expression  for  the  amount  of  solvent 
remaining  in  the  solution  at  the  moment  of  observation  is 
therefore  — 

[809]  g70.M(/-g) 

760(l+aO 

where  a = grams  of  solvent  originally  present  ;/= the  tension 
at  the  temperature  t  of  the  pure  solvent,  expressed  in  milli- 
metres of  mercury;  0=the  depression  of  tension,  also  in  terms 
of  millimetres  of  mercury;  w= weight  in  grams  of  1  cc.  of  the 
vapor  under  standard  conditions.  Now  if  b = the  weight  of  io- 
dine in  the  solution,  and  p  -  the  ratio  of  solvent  to  iodine  — 

b 


I.  p- 


270  .  w  .  (f-e) 
760  .  (1+ctf) 


The  concentration  being  thus  ascertained,  the  calculation 
of  the  molecular  weight  of  iodine  was  made  according  to  the 
formula  — 


MOLECULAR  WEIGHT  OF  IODINE     235 

n. 

MI  and  Mo  being  the  molecular  weights  of  iodine  and  solvent 
respectively.  This  is  a  working  formula  derived  by  Raoult 
from  an  expression  for  the  relation  between  the  ratio  of  mole- 
cules of  solvent  and  substance  dissolved  on  the  one  hand,  and 
the  ratio  between  the  tension  of  the  pure  solvent  and  the 
depressed  tension  on  the  other,  where  the  dissolved  substance 
itself  has  a  comparatively  insignificant  tension.  It  is  interest- 
ing to  note  that  the  latter  expression  was  reached  independ- 
ently and  almost  simultaneously  by  Planck.1 

In  the  following  tabulated  statement  of  my  observations, 
the  first  two  columns  show  the  weights  of  the  ingredients 
of  the  solution  originally  introduced;  the  third  gives  the  tem- 
perature; the  fourth,  the  depression  of  tension;  the  fifth,  the 
true  tension  of  the  solution;  the  sixth,  the  concentration  as 
calculated  by  formula  I;  finally,  we  have  the  molecular  weight 
as  calculated  by  formula  II.  Before  giving  the  results  ob- 
tained for  iodine,  I  think  it  useful  to  give  a  summary  of  a 
few  test  experiments  made  on  the  molecular  weight  of  naph- 
thalene, which  not  only  proved  the  trustworthiness  of  the 
method,  but  also  showed  that  there  is  no  specific  difference 
between  ether  and  carbon  bisulphide  which  could  invalidate 
the  effect  of  the  great  difference  of  the  molecular  weights 
found  for  iodine. 

1  Compare  Raoult,  Zeilschr.  physik.  Chem.  2,  372  (1889),  and  Planck,  ibid.  2, 

408  (1888).    ,  [EDITOR.] 


236  MORRIS  LOEB 

[810]  NAPHTHALENE  IN  CARBON  BISULPHIDE 


a 

b 

t 

e 

f-6 

P 

M1 

Average 

5-4082 

0  2586 

27-5° 
27-5 

9-47 
10-93 

377-09 
375-65 

5-18 
5-18 

129 
135 

|l32 

NAPHTHALENE  IN  ETHYL  ETHER 


a 

b 

t 

e 

f-e 

P 

Mt 

Average 

2-8359 

0-1462 

27-5° 

21-12 

557-27 

6-53 

127 

1 

I 

I 

27-5 
27  5 

21-08 
21-14 

557-31 
557-25 

6-53 
6-53 

128 
127 

I  127-5 

— 

— 

27  5 

21-17 

557-22 

6  53 

128 

J 

Average  in  CS2   MI  =  132 

Average  in  C4Hi0O MI  =  127-5 

Theory  for  Ci0H8 MI  =  128. 


IODINE  IN  CARBON  BISULPHIDE 


a 

b 

t 

e 

f-e 

P 

M, 

Average 

5-6528 

0-4388 

27-3° 

9-72 

373-92 

8-37 

239 

1 

— 

— 

27  3 

8-59 

375-05 

8-37 

278 

I    0«, 

— 

— 

27  3 

8-81 

374-83 

8-37 

271 

f  264 

- 

— 

27  3 

9-08 

374  56 

8-37 

268 

J 

5-1862 

0-4026 

27-5 

8-10 

378-48 

8-46 

300-5 

} 

— 

27-5 

8-10 

378-48 

8'46 

300-5 

J-  300'5 

5-4579 

0  2594 

27-5 

4-60 

381-98 

5-15 

324 

1 





27-5 

4-51 

382-07 

5-15 

332 

_ 

_ 

27-5 

4-66 

381-92 

5-15 

320 

[  320 

— 

— 

27-5 

4-76 

381-82 

5-15 

314 

f 

— 

— 

27-55 

4-80 

382-52 

5-15 

310 

J 

4-9030 

0-2330 

27-5 

4-67 

381-91 

5-20 

326 

1    39ft  •  f\ 

— 

— 

27-5 

4-60 

381-98 

5-20 

327 

s    Oiov    O 

Total  average MI  =  303-25  ±  5-10 

Theory  for  I2 MI  =  254 

Theory  for  I3 MI  =  381. 


MOLECULAR  WEIGHT  OF  IODINE     237 

[811]  IODINE  IN  ETHYL  ETHER 


a 

b 

t 

e 

f~e 

P 

M, 

Average. 

3-2578 

0  2546 

27-2° 

8-20 

563-69 

9-59 

488 



— 

27-2 

7-50 

564-39 

9-59 

534 

— 

_ 

27-2 

7-81 

564-08 

9-59 

512 

504-7 

_ 

— 

27-35 

8-09 

567-05 

9-60 

497 

— 

— 

27  3 

8-16 

565-90 

9-60 

492-5 

3-2864 

0-2058 

27  3 

7-46 

566-60 

7-68 

443 

1 

— 

— 

27  3 
27  3 

4-84 
5-04 

569-22 
569-02 

7-68 
7-68 

653 
642 

I  577-2 

— 

— 

27  3 

5-66 

568-40 

7-68 

571 

J 

3-6809 

0-2305 

27-4 

6-51 

569-72 

7-50 

486-5 

1 

27-4 
27-45 

6-48 
6  77 

569-75 
570-54 

7-50 
7-51 

487 
468-5 

I  480-7 

3  4343 

0-3151 

27-5 

6  99 

571-40 

7-62 

461 

] 

I 

I 

27  5 
27  5 

7-14 
6  43 

571-25 
571-96 

7  62 

7-62 

451 
501-5 

I  466-1 

— 

— 

27-5 

7-14 

571  25 

7-62 

451 

J 

Total  average MI  =  507*2  ±  10'5 

Theory  for  I4 MI  =  508. 


It  seems  very  probable,  therefore,  that  iodine  in  its  red  so- 
lutions has  a  molecular  weight  corresponding  to  1^  whilst  in 
the  violet  solution  in  carbon  bisulphide  there  is  a  less  complex 
aggregation,  giving  a  value  between  12  and  Is.  I  may  as  well 
remark  that  the  values  for  p  in  the  ether  solutions  correspond 
approximately  with  the  ratio  of  one  iodine  molecule  in  100 
molecules  of  the  solutions;  in  the  carbon  bisulphide  solutions, 
this  ratio  varies  between  1 : 100  and  1 :  200.  Whilst  greater 
dilution  might  appear  more  advisable  from  a  theoretical  point 
of  view,  it  offers  an  apparently  insurmountable  difficulty  in 
practice.  A  glance  at  the  formulae  used  in  the  calculation 
shows  that  the  value  of  e  enters  three  times  in  such  a  manner 
that  any  error  attached  to  it  would  be  tripled.  As  e  decreases 
with  the  concentration,  it  is  evident  that  a  greater  dilution 
than  that  employed  by  me  will  soon  bring  e  to  a  point  where 


238  MORRIS  LOEB 

the  chance  errors  of  observation  become  proportionately  very 
great.  Hence  I  agree  with  Raoult  when  he  says  that  the 
method  of  determining  molecular  weights  by  the  depression 
of  the  freezing-point  is  preferable  to  the  method  by  vapor 
tensions.  But  for  the  problem  which  immediately  interested 
me  I  lacked  a  liquid  which  would  solidify,  and  also  dissolve 
iodine  with  a  pure  violet  color,  benzene,  for  instance,  giving 
a  very  [812]  impure  bluish-brown.  Nevertheless  I  endea- 
vored to  obtain  what  corroborative  evidence  I  could  by  experi- 
menting on  the  freezing  points  of  iodine  in  acetic  acid  and  in 
benzene,  but  was  forced  to  give  up  the  attempt  by  the  very 
slight  solubility  of  iodine  in  these  menstrua  at  low  tempera- 
tures; the  molecular  weight  of  iodine  as  calculated  from  vari- 
ous series  of  observations  seemed  to  increase  continuously 
with  the  concentration,  so  that  there  was  no  point  in  the  nar- 
row limits  between  extreme  dilution  and  saturation  at  which 
the  molecular  weight  would  appear  constant,  and  could  be 
accepted  as  trustworthy.  A  paper  published  since  then  by 
Paterno  and  Nasini1  on  this  subject  contains  a  few  figures 
for  the  molecular  weight  of  iodine  in  acetic  acid  and  benzene 
solutions,  but  I  am  unable  to  draw  any  other  inference  from 
them  than  from  my  own. 

1  Berichte,  21,  2155  (1888). 


[606]    UEBER  DEN  MOLEKULARZUSTAND  DES 
GELOESTEN  JOBS1 

DAS  Jod  lost  sich  bekanntlich  in  Schwefelkohlenstoff  und 
Kohlenwasserstoffen  mil  violetter  Farbe,  in  Alkohol,  Aether 
und  andern  Alkoholderivaten  dagegen  rotbraun  auf,  einer- 
seits  seiner  Dampfform,  andererseits  seinem  festen  Zustande 
entsprechend.  Man  folgert  gewohnlich  daraus,  dass  das  Jod 
diese  Zustande  in  den  Losungen  behielte,  oder,  genauer  ge- 
sprochen,  dass  die  rote  Farbe  komplexere  Molekel 2  andeute 
als  die  violette.  Eine  quantitative  Stiitze  dieser  Annahme 
hat  sich  meines  Wissens  bisher  nicht  erforschen  lassen; 
qualitativ  allerdings  sprechen  Analogieen  in  den  Absorptions- 
spektren  dafiir,  sowie  eine  Beobachtung  E.  Wiedemanns,3 
wonach  eine  Losung  von  Jod  in  Schwefelkohlenstoff  bei 
starker  Abkiihlung  aus  violett  in  rotbraun  ubergeht.  In  der 
That  wird  die  erste  versprechende  Aussicht  auf  Beantwortung 
derartiger  Fragen  liber  die  Elemente  durch  jene  Beziehungen 
eroffnet,  welche  neuerdings  Raoult  zwischen  den  Molekular- 
zustanden  einerseits  und  Aenderungen  in  der  Dampftension 
und  dem  Gefrierpunkte  des  Losungsmittels  andererseits  her- 
vorgehoben,  und  van  't  Hoff  mathematisch  hergeleitet  hat. 
Auf  Veranlassung  Herrn  Professor  Ostwalds  habe  ich  nun 
Versuche  angestellt,  um  zu  erfahren,  ob  sich  wirklich  eine 
Verschiedenheit  des  Molekulargewichts  des  Jods  in  seinen 
Losungen  aus  den  Dampfdruckserniedrigungen  derselben 
ergiebt:  ich  glaube  dies  jetzt  entschieden  bejahen  zu  konnen. 

Die  Wahl  des  Losungsmittels  war  nicht  schwer,  da  Aether 

1  Reprinted  from  Zeitschrift  fur  physikalische  Chemie,  2,  606  (1888). 

2  This  now  almost  obsolete  spelling  was  generally  used  in  1888.       [EDITOR.] 
8  Phys.-Med.  Gesell.  Erlangen  (1887). 


240  MORRIS  LOEB 

und  Schwefelkohlenstoff,  welch e  beide  sehr  hohe  Dampf- 
spanmmg  besitzen,  den  Farbenunterschied  in  besonders 
schoner  Weise  zeigen  und  daher  fur  typisch  gel  ten  konnen, 
wahrend  viele  andere  Losungsmittel,  wie  Benzol,  die  unrei- 
nen  Nuancen  eines  Uebergangszustandeshervorbringen.  Da- 
gegen  liess  sich  die  Raoultsche  Methode,  die  Losungen  in 
die  Barometerleere  einzufiihren  und  den  Quecksilberstand 
direkt  zu  messen,  deshalb  nicht  anwenden,  weil  [607]  eine  Be- 
riihrung  zwischen  Jod  und  Quecksilber  nicht  statthaft  war. 
Es  hat  sich  indeiSsen  eine  Modification  eines  Regnaultschen 
Apparates  als  niitzlich  erwiesen,  welche  eine  bequemere 
Handhabung  und  raschere  Ausfiihrung  gestattet,  genaue 
Messinstrumente  unnotig  macht  und,  trotz  einiger  neuen 
Fehlerquellen,  hinreichende  Genauigkeit  besitzt,  Fragen  wie 
die  vorliegende  zu  entscheiden. 

Zwei  Reagensflaschen  von  annahernd  gleichem  Gehalt 
erhalten  guteingeschliffene,  hohle  Glasstopsel,  welche  beider- 
seits  offen  sich  nach  oben  in  Glasrohren  aus  starkem  Glase, 
von  etwa  6  mm.  lichter  Weite,  fortsetzen.  Diese  Rohren  wer- 
den  zweimal  rechtwinklig  gebogen,  so  dass  der  unten  offene 
Schenkel  50  cm.  lang  ist,  wahrend  der  andere  Schenkel  und 
der  wagrechte  Teil  nur  je  etwa  105  cm.  lang  sind.  Diese 
beiden  Rohren  werden  untereinander  durch  Stiicke  dicken 
Gummischlauchs,  deren  eines  einen  Quetschhahn  fiihrt, 
unter  Vermittelung  eines  T-Rohres  verbunden.  Das  dritte 
Ende  dieses  T-Rohres,  —  zweckmassig  nach  oben  gekehrt, 
statt  wie  der  Uebersichtlichkeit  halber  gezeichnet,  —  dient 
zur  Verbindung  nach  aussen  und  ist  deshalb  mit  Schlauch 
und  Quetschhahn  versehen.  Es  werden  nun  die  Flaschen  mit 
den  die  Flussigkeiten  enthaltenden  Rohrchen  beschickt, 
welche  aus  oben  und  unten  stumpfwinklig  ausgezogenen 
diinnwandigen  Glasrohren  gefertigt  sind,  2  bis  3  cc.  fassen 
und  nach  dem  Fiillen  vor  der  Stichflamme  geschlossen  wer- 


DAS  GELOESTE  JOD 


241 


den.    In  die  eine  Flasche  kommt  die  Losung,  in  die  andere 

das  reine  Losungsmittel :  die  Flaschen  werden  geschlossen, 

nachdem  noch  zu  besserer  Dichtung  die 

Stopsel  mit  syrupsdicker  Phosphorsaure- 

losung  bestrichen  worden.    Das  offene 

Ende  der  T-Rohre  wird  mit  einem  Rohre 

verbunden,  das    auf   den   Boden   einer 

WoulfTschen  Flasche  reicht,  welche  mit 

gef  arbtem  Wasser  gefiillt  ist  und  mittels 

ihrer  anderen  Miindung  mit  einer  Luft- 

pumpe  kommuniziert.    Die  Luft  im  Ap- 

parate  wird  so  lange  verdiinnt,  bis  der 

Unterdruck  den  zu  erwartenden  hb'ch- 

sten  Druck  um  weniges  ubertrifft,  der 

Quetschhahn    alsdann  geschlossen  und 

die  WoulfTsche  Flasche  mit  der  Aussen- 

luft  in  Verbindung  gesetzt.    Durch  vor- 

sichtiges  Oeffnen  des  Hahnes  lasst  man 

nun  so  viel  Wasser  in  die  Rohren  treten,  dass  dasselbe  die  Half  te 

der  langen  Schenkel  erfiillt.    Man  entfernt  die  Woulffsche 

Flasche  und  hat  nun  ein  empfindliches  [608]  Differentialmano- 

meter,  welches  Druckunterschiede  in  Wasserhohe  direkt  an- 

giebt,  vom  ausseren  Druck  ganz  unabhangig  ist  und  wegen  der 

verschwindenden  Verschiebung  der  Volume  in  beiden  Halften 

(die  grosste  beobachtete  Differenz  bedingte  kaum  einen  hal- 

ben  cc.,  wahrend  die  Flaschen  270  cc.  fassen)  hierfiir  eine  Kor- 

rektion  unnotig  machte.   Der  Kapillaritatseinfluss  hebt  sich 

gegenseitig  auf  und  die  im  Apparate  verbleibende  Luft  ubt  auf 

beiden  Seiten  gleichen  Druck  aus,  so  dass  ein  Verdiinnen  der- 

selben  bloss  zum  Vermeiden  eines  grossen  Druckunterschiedes 

zwischen  dem  Innern  des  Apparates  und  der  Atmosphare, 

wodurch  bei  langerem  Stehen  ein  Austreiben  der   Stopsel 

und  folgliche  Undichtigkeit  haufig  vorkam,  notig  war.    Es 


242  MORRIS  LOEB 

ergab  sich  aber  auch  der  weitere  Vorteil,  dass  eine  schnelle 
Verbreitung  des  Dampfes  ermoglicht  ward,  wodurch  die 
Dauer  der  Versuche  eine  kiirzere  wurde.  Der  Versuch  wurde 
folgendermassen  fortgefiihrt:  die  Flaschen  wurden  dicht  zu- 
sammen  in  einen  Wasserthermostaten  bis  an  den  oberen 
Rand  des  Halses  gesteckt,  wahrend  die  beiden  Manometer- 
rohren  ausserhalb  desselben  ebenfalls  dicht  beisammen  her- 
abhingen.  Nachdem  an  einer  lotrecht  daneben  hangenden 
Skala  mit  Millimeterteilung  die  kleine  Niveaudifferenz  fest- 
gestellt,  wurde  die  Verbindung  der  beiden  Halften  mittels 
des  hierzu  angebrachten  Quetschhahns  aufgehoben  und  die 
Rohrchen  durch  Schiitteln  der  Flaschen  geoffnet.  Es  dauerte 
eine  Viertelstunde  ehe  man  die  Verbindung  wieder  herstel- 
len  durfte,  ohne  ein  Ueberspritzen  der  Sperrfliissigkeit  in  die 
eine  oder  die  andere  Flasche  befiirchten  zu  miissen;  dann 
aber  stellte  sich  rasch  ein  Gleichgewichtszustand  her,  der 
manchmal  viele  Stunden  lang  unverandert  blieb,  manchmal 
aber  um  Centimeter  Wasserdruck  schwankte.  Die  Ursache 
des  Schwankens  lag  wohl  in  ungleichmassiger  Verteilung 
der  Losung  in  der  Flasche  und  an  kleinen  Temperatur- 
schwankungen,  welche  die  Witterung  der  letzten  Wochen 
sehr  begtinstigte.  Nach  eintagigem  Stehen  war  kein  Ver- 
trauen  mehr  in  die  Werte  zu  setzen,  da  alsdann  die  Diffu- 
sion des  Wasserdampfes  bis  zur  Flasche  vorgeschritten  war, 
die  Fliissigkeiten  nicht  mehr  trocken  waren. 

Die  nun  mit  Riicksicht  auf  die  urspriingliche  Differenz 
korrigierten  Unterschiede  des  Wasserstandes  ergaben  also 
den  Unterschied  zwischen  der  Spannung  des  reinen  Losungs- 
mittels  und  der  jeweiligen  Losung;  d.  i.  die  Erniedrigung, 
welche  die  gerade  in  der  Losung  bestehende  Konzentration 
des  Jods  bewirkte.  Zur  Berechnung  dieser  Konzentration 
brauchte  ich  zweierlei  Daten:  die  Mengen  des  thatsachlich 
vorhandenen  Jods  und  Losungsmittels,  und  die  Menge  des 


DAS  GELOESTE  JOD  243 

letzteren,  welches  in  Gasform  der  Losung  sich  entzogen  hatte. 
Die  Rohrchen  enthielten  deshalb  gewogene  Mengen  der  einer 
frisch  bereiteten  Mischung  der  abgewogenen  Bestandteile 
entnommenen  [609]  Losung.  Andererseits  liess  sich  die  ver- 
dampfte  Menge  des  Losungsmittels  nach  bekanntem  gaso- 
metrischen  Gesetze  berechnen,  wenn  man  nur  den  Druck, 
unter  welchem  dasselbe  stand,  kannte :  derselbe  ist  gleich  dem 
der  reinen  Fltissigkeit,  vermindert  um  die  abgelesene  Er- 
niedrigung.  Wie  ich  mich  durch  direkte  Versuche  uberzeugte, 
genligen  die  durch  Interpolation  aus  den  Regnaultschen 
Zahlen  erhaltenen  Werte  fur  die  reinen  Fliissigkeiten  voll- 
kommen  den  Anspriichen  meiner  Versuche.  Es  sei  nun  p  das 
Verhaltnis  des  in  der  Fliissigkeit  augenblicklich  vorhandenen 
Losungsmittels  zu  dem  darin  aufgelosten  Jod;  a  die  einge- 
wogene  Menge  des  Losungsmittels  in  Gramm  ausgedriickt, 
b  die  des  Jods;/  der  berechnete  Quecksilberdruck  des  Gases 
Uber  der  reinen  Fliissigkeit,  e  die  gefundene  Erniedrigung 
gleichfalls  in  Millimeter  Quecksilberhohe  ausgedriickt;  g  das 
Gewicht  eines  Kubikcentimeters  des  Dampfes  bei  0°  und 
760  mm.  Dann  haben  wir,  das  Volum  der  Flasche  gleich  270 
cc.  gesetzt,  fur  das  Gewicht  des  in  dem  fliissigen  Teil  ver- 
bliebenen  Losungsmittels  den  Ausdruck 


760  .  (l+o0 

und  daher 

i 
I.  p=- 


760(1+00 

Der  weiteren  Berechnung  lege  ich  eine  Formel  zu  Grunde, 
welche  Raoult  1  jiingst  aufgestellt  hat,  die  ihrerseits  auf  dem 

1  Zetochr.  2,  372  (1888). 


244 


MORRIS  LOEB 


von  ihm  und  Planck  1  ubereinstimmend  gefundenen  Gesetz 
fur  die  Losungen  wenigfliichtiger  Substanzen  beruht.  Diese 
Formel  lautet 


II. 


wobei  MQ  das  Molekulargewicht  des  Losungsmittels,  MI 
dasjenige  des  gelosten  Korpers  bedeutet.  In  den  tabellari- 
schen  Zusammenstellungen  meiner  Versuche  gebe  ich,  be- 
hufs  besserer  Uebersicht,  in  den  beiden  ersten  Kolumnen  die 
Gewichte  der  Ingredienzen  der  eingefiihrten  Losung,  in  der 
dritten  die  Temperaturen,  in  der  vierten  die  gefundene  Er- 
niedrigung  in  Millimeter  Quecksilber,  in  der  fiinften  den 
berechneten  Dampfdruck  der  Losung,  in  der  sechsten  die 
Werte  fur  p  und  endlich  das  sich  ergebende  Molekulargewicht 
des  Jods.  Zur  Beurteilung  der  Methode  mogen  die  Mes- 
sungen  dienen,  welche  ich  an  einem  Korper  von  zweifellos 
konstantem  [610]  Molekulargewicht,  dem  Naphthalin,  aus- 
gefiihrt:  ich  schicke  dieselben  deshalb  voraus. 


NAPHTHALIN  IN  SCHWEFELKOHLENSTOFF 


a 

b 

t 

e 

f-e 

P 

Ml 

5-4082 

0-2586 

27-5° 

9-47 

377-09 

5-18 

129 

— 

— 

27-5 

10-93 

375  65 

5-18 

135 

Mittel  der  gefundenen  "Werte  132. 
Berechnet  fur  Ci0H8  128. 

1  Zeitschr.  2,  408  (1888). 


DAS  GELOESTE  JOD 


245 


NAPHTHALIN  IN  AETHER 


a 

b 

t 

6 

/- 

P 

Jf, 

Mittelwert 

2-5990 

0  2511 

27-5° 

32-84 

535  55 

12-47 

150i 

2-8359 

0-1462 

27-5 

21-12 

557-27 

6-53 

127 

— 

— 

27-5 

21-08 

557-31 

6  53 

128 





27-5 

21-14 

557-25 

6-53 

127 

127-5 

— 

— 

27-5 

21-17 

557  22 

6  53 

128 

ber.  128 

JOD  IN  SCHWEFELKOHLENSTOFF 


a 

b 

t 

e 

f-e 

P 

J/i 

Mittel 

5-6528 

0-4388 

27-3° 

9  72 

373-92 

8-37 

239 





27  3 

8-59 

375-05 

8-37 

278 

264 



— 

27  3 

8.81 

374-83 

8-37 

271 

— 

— 

27  3 

9-08 

374-56 

8-37 

268 

5-1862 

0-4026 

27-5 

8-10 

378-48 

8-46 

300-5 

300-5 

— 

— 

27-5 

8-10 

378-48 

8-46 

300-5 

5-4579 

0-2594 

27-5 

4-60 

381  •  98 

5-15 

324 

— 

— 

27-5 

4-51 

382-07 

5-15 

332 





27-5 

4-66 

381-92 

5-15 

320 

320 





27-5 

4-76 

381-82 

5-15 

314 

— 

— 

27-55 

4-80 

382-52 

5-15 

310 

4-9030 

0-2330 

27-5 

4-67 

381-91 

5-20 

326 

326-5 

~~ 

— 

27-5 

4-60 

381-98 

5-20 

327 

Mittelwert  aller  Versuche  J/i  =  303  -25  ±5'  10  2 
Berechnet  ftlr  J2,  Mt  =  254. 
"    /„  Ml  =  381. 

1  Dieser  Versuch  war  mit  zu  konzentrierter  Losung  angestellt,  um  in  Be- 
tracht  zu  kommen. 


2  Der  wahrscheinliche  Fehler  1st  nach  der  Form  el  F=  ±  f 
berechnet.  Der  mittlere  wahrscheinliche  Versuchsfehler 
betragt  19. 


+/«' 


« 


246 


MORRIS  LOEB 


[611]  JOB  IN  AETHER 


a 

c 

t 

e 

f-e 

P 

M, 

Mittel 

3-2578 

0-2546 

27-2° 

8-20 

563  69 

9-59 

488 





27-2 

7-50 

564-39 

9-59 

534 

— 



27-2 

7-81 

564-08 

9-59 

512 

504-7 

— 

— 

27-35 

8-09 

567-05 

9-60 

497 

— 

— 

27-3 

8-16 

565-90 

9-60 

492-5 

3-2864 

0-2058 

27-3 

7-46 

566-60 

7-68 

443 





27-3 

4-84 

569-22 

7-68 

653 

577-2 





27-3 

5-04 

569-02 

7-68 

642 

— 

— 

27  3 

5-66 

568-40 

7-68 

571 

3-6809 

0  2305 

27-4 

6-51 

569-72 

7-50 

486-5 

— 



27-4 

6-48 

569-75 

7-50 

487 

480-7 

— 

— 

27-45 

6-77 

570-54 

7-51 

468-5 

3  4343 

0-3151 

27-5 

6  99 

571-40 

7-62 

461 

— 

— 

27-5 

7-14 

571-25 

7-62 

451 

466-1 

— 

— 

27-5 

6-43 

571-96 

7-62 

501-5 

— 

— 

27-5 

7-14 

571-25 

7-62 

451 

Mittel  aller  Versuche  Ml  =  507'2±10'5. 
Wahrscheinlicher  Fehler  ernes  Versuchs  =  42. 
Berechnet  fur  J4,  M^  =  508. 

Aus  diesem  Material  ergiebt  sich  mil  grosser  Wahrschein- 
lichkeit,  dass  das  Jod  in  roter  Losung  ein  der  Formel  7  4  ent- 
sprechendes  Molekulargewicht  besitzt,  wahrend  sich  aus  der 
Schwefelkohlenstofflosung  ein  halbwegs  zwischen  72  und  73 
stehender  Wert  berechnet.  Um  den  Vergleich  mit  andern 
Berechmmgsweisen  zu  erleichtern,  mache  ich  noch  darauf 
auf  merksam,  dass  meine  Werte  fur  p  bei  Aetherlosungen  un- 
gefahr  einer  Molekel  74  auf  hundert  Molekel  des  Gemenges 
entsprechen,  wahrend  in  den  Schwefelkohlenstofflosungen 
das  Verbal tnis  zwischen  1  : 100  und  2  : 100  schwankte.  Dass 
sich  grossere  Verdiinnungen  bei  dieser,  sowie  der  Raoultschen 
Versuchsordnung  verbieten,  wird  klar,  wenn  man  bedenkt, 
dass  der  Wert  e  in  der  Berechnung  dreimal  auftritt  und  man 
denselben  daher  nicht  sich  so  verkleinern  lassen  darf ,  dass  die 


DAS  GELOESTE  JOD  247 

Beobachtungsfehler  verhaltnissmassig  bedeutend  werden. 
Es  ware  daher,  wie  schon  Raoult  beiuerkt,  iiberhaupt  die 
Gefrierpunktsmethode  der  Dampfspannungsmethode  immer 
vorzuziehen.  Um  das  mir  vorgesteckte  Ziel  zu  erreichen, 
fehlte  es  mir  aber  vor  allem  an  einem  gefrierbaren  Losungs- 
mittel,  welches  das  Jod  mit  reinvioletter  Farbe  loste;  Benzol 
giebt,  wie  schon  erwahnt,  eine  Mischfarbe.  Trotzdem  habe 
ich  im  Verlaufe  der  Untersuchung  Versuche  iiber  die  Gefrier- 
punkte  der  Losungen  von  Jod  in  Benzol  sowohl,  [612]  wie  in 
Eisessig  angestellt.  Ich  gab  dieselben  aber  auf,  als  ich  mich 
Uberzeugt,  dass  bei  der  sehr  geringen  Loslichkeit  des  Jods  in 
den  erwahnten  Fllissigkeiten  ein  geniigender  Spielraum  nicht 
vorhanden  ist:  das  berechnete  Molekulargewicht  nahm  von 
der  aussersten  Verdiinnung  bis  zur  Sattigung  stetig  mit  der 
Konzentration  zu,  so  dass  sich  kein  Punkt  zeigte,  bei  welchem 
man  einen  Vorzug  iiber  die  andern  erkennen  konnte.  Die 
jiingst  von  den  Herren  Paterno  und  Nasini 1  veroffentlichten 
Zahlen  scheinen  mir  Aehnliches  zu  ergeben. 

Herrn  Professor  Ostwald  freue  ich  mich  fur  das  liebens- 
wiirdige  Interesse,  welches  er  mir  wahrend  dieser  unter 
seiner  Leitung  ausgefiihrten  Arbeit  gezeigt,  hier  offentlich 
danken  zu  diirfen. 

1  Berichte,  21,  2155  (1888). 


[812]    THE  USE  OF  ANILINE  AS  AN  ABSORB- 
ENT OF  CYANOGEN  IN  GAS  ANALYSIS1 

IN  a  paper  published  in  the  "Comptes  Rendus,"  100, 
1005,  some  time  ago,  Jaquemin  proposed  the  use  of  aniline 
as  an  absorbent  for  cyanogen  in  quantitative  gas  analysis, 
without,  however,  giving  details  of  any  experiments  as  to  the 
trustworthiness  of  the  method.  The  proposal  is  a  surprising 
one,  considering  that  hydrogen  cyanide  is  always  formed  in 
the  preparation  of  cyananiline;  this  fact  is  distinctly  stated 
by  Hofmann,2  who  accounted  for  its  production  by  certain 
secondary  reactions  which  he  studied.  It  is  also  to  be  noted 
that  Jaquemin,  in  the  same  paper,  describes  a  very  satisfac- 
tory method  of  preparing  cyanogen  gas  in  the  wet  way,  and 
that  he  probably  employed  the  moist  cyanogen  in  his  experi- 
ments with  aniline.  As  the  presence  of  water  seems  to  favor 
most  of  the  reactions  of  cyanogen,  there  did  not  seem  to  be 
any  conclusive  evidence  that  dry  cyanogen  would  be  totally 
absorbed  by  aniline.  At  all  events,  it  seemed  worth  while  to 
make  the  experiment  with  cyanogen  prepared  in  the  old  way, 
and  at  the  same  time  to  ascertain  to  what  extent  the  develop- 
ment of  hydrocyanic  acid  would  interfere  with  Jaquemin's 
proposed  method  for  gas  analysis.  For  this  purpose,  cyano- 
gen prepared  from  dry  mercuric  cyanide  was  brought  into 
contact  with  recently  distilled  aniline.  The  gas  was,  indeed, 
absorbed  rapidly  and  completely,  nor  did  a  bubble  of  gas 
appear  after  twenty-four  hours'  standing.  But  as  soon  as  car- 
bon dioxide  was  passed  in,  the  presence  [813]  of  hydrocyanic 

1  Reprinted  from  Journal  of  the  Chemical  Society,  63,  812  (October,  1888). 

2  Hofmann,  Annalen,  66,  129  (1848). 


ANILINE  AS  ABSORBENT  OF  CYANOGEN  249 

acid  became  apparent.  It  was  expelled  from  the  aniline  by 
the  carbon  dioxide,  and  could  now  be  recognized  both  by  its 
odor  and  by  the  Prussian  blue  reaction.  At  the  same  time  a 
considerable  quantity  of  carbon  dioxide  is  absorbed  by  the  ani- 
line and  must  be  held  in  solution,  as  chemical  union  is  impos- 
sible under  the  circumstances.  As  the  same  is  said  to  be  the 
case  with  carbon  monoxide,  and  these  two  gases  are  those 
which  generally  accompany  cyanogen,  I  fail  to  see  how  aniline 
can  be  generally  useful  in  determining  the  amount  of  cyano- 
gen in  a  mixture,  apart  from  the  fact  that  hydrogen  cyanide 
is  produced  in  the  reaction,  and  is  itself  very  loosely  attracted 
by  aniline. 

The  experiments  by  which  I  satisfied  myself  of  this  were 
made  last  April,  in  the  laboratory  of  the  Physical  Association 
of  Frankfort-on-Main,  to  the  director  of  which,  Dr.  B.  Lep- 
sius,  I  am  very  much  indebted.  The  details  of  a  few  of  the 
most  important  tests  are  given  below. 

I.  32*88  cc.  of  cyanogen  gas  (under  standard  conditions) 
were  absorbed  immediately  by  12*5  cc.  aniline;  after  twenty- 
five  hours  no  trace  of  gas  had  been  evolved. 

II.  A  mixture  of  cyanogen  and  dry  air  was  introduced  into 
a  T-shaped  eudiometer,  provided  with  stopcocks  and  filled 
with  mercury.  Aniline  was  first  added  and  allowed  to  absorb 
the  cyanogen,  and  dry  carbon  dioxide  was  then  passed  in; 
when  no  further  change  took  place,  the  unabsorbed  gas  was 
transferred  to  a  test-tube  over  mercury,  and  brought  in  con- 
tact with  a  few  drops  of  sodic  hydrate;  the  alkaline  solution 
gave  an  appreciable  test  for  hydrocyanic  acid  with  ferrous 
and  ferric  salts.   In  the  table  [on  the  following  page]  the 
measurements  and  the  results  are  given:  — 


250 


MORRIS  LOEB 


t 

B 

cc 

Corrected 

Volume  of  cyanogen  and  air  .  . 
Volume  22  hours  after  introduc- 
ing aniline  

19-0° 
19-5 

752-1 
752-1 

60 

7-7 

55-34 
7-09 

- 

Volume  of  cyanogen  absorbed  . 
After  addition  of  carbon  dioxide 
Volume  carbon  dioxide 

19~5 

752-1 

36-75 

33~84 

48-25 
26-75 

After  23  '5  hours  .  ... 

19-5 

752-0 

21-00 

19  33 

Volume  carbon  dioxide  absorbed 

14-51 

III.  A  similar  experiment,  performed  in  a  somewhat  dif- 
ferent order,  and  with  the  use  of  a  straight  eudiometer,  gave 
an  analogous  result.  H =the  height  of  the  column  of  mercury, 
h  =  the  height  of  the  column  of  aniline  reduced  to  mercury. 

[814] 


t 

B 

H 

n 

cc 

Corrected 

Volume  of  carbon  dioxide  .... 
Volume  of  carbon  dioxide  and 
cyanogen  ... 

19-5° 
19-5 

752-1 
752-1 

- 

- 

56-5 

108-5 

52-03 
99-91 

Volume  of  cyanogen        .... 

47'88 

Vol.  22  hours  after  introduction 
of  aniline  .... 

19-5 

752-0 

227 

5-3 

43-0 

27-32 

Volume  of  gas  absorbed  

72-59 

47*88  cc.  cyanogen  gas  and  24*71  cc.  carbon  dioxide  have, 
therefore,  been  absorbed.  In  this  case,  too,  the  residual  gas 
had  a  decided  odor  of  prussic  acid. 


[948]    ZUR  KINETIK  DER  IN  LOSUNG  BEFIND- 
LICHEN  RORPER1 

1.   ElNLEITUNG 

BEKANNTLICH  hat  Herr  Fr.  Rohlrausch,2  ausgehend  von 
der  Hittorfschen  Hypothese,  wonach  die  Ueberfiihrungszahl 
einer  Losung  das  Verhaltnis  der  Geschwindigkeiten  der  beiden 
Jonen,  in  welche  das  in  Losung  befindliche  Salz  zerfallt, 
berechnen  lasst,  zwischen  dieser  Grosse  und  dem  elektrischen 
Leitungsvermogen  eine  einfache  Beziehung  aufgestellt.  Hier- 
nach  ist  das  Leitungsvermogen  X  eine  additive  Eigenschaft, 
namlich  gleich  der  Summe  der  Beweglichkeiten  des  Anions 
v  und  des  Rations  u.  Die  Ueberfiihrungszahl  eines  Jons  ist  das 
Verhaltnis  der  Beweglichkeit  dieses  Jons  zu  der  Summe  der 
Beweglichkeiten  der  beiden  Jonen.  Es  ist  somit,  wenn  n  die 
Ueberfiihrungszahl  des  Anions,  und  somit  l—n  dieselbe 
Grosse  fur  das  Ration  bedeutet:  — 

~  u 

l-n=- 


u+v  u+v 

Diese  Beziehungen  fand  Herr  Rohlrausch  an  einer  Anzahl 
Verbindungen  einbasischer  Sauren  sowie  an  einigen  ein- 
wertigen  Basen  in  Losungen  geringer  Ronzentrationen  gut 
bestatigt;  schwache  Basen  (z.  B.  Ammoniak)  und  Sauren 
(z.  B.  Essigsaure)  fiigten  sich  selbst  bei  betrachtlichen  Ver- 
diinnungen  auch  nicht  naherungsweise  unter  obige  Gesetze. 

Diesen  Widerspruch  zwischen  Theorie  und  Erfahrung  hat 
kiirzlich  Herr  Arrhenius  3  durch  Einfiihrung  des  Aktivitats- 
begriffes  gehoben.  Das  Leitungsvermogen  kann  nur  in  dem 

1  In  collaboration  with  W.  Nernst.    Reprinted  from  Zeitschr.  2,  948  (1888). 

2  Fr.  Kohlrausch,  Wied.  Annalen,  6,  1  (1879).   Ibid.,  26,  213  (1885). 

1  Arrhenius,  Sur  la  conductibilite,  etc.  Stockholm,  1884.  Zeitschr.  1,  631  (1887). 


252  MORRIS  LOEB 

Falle  eine  additive  Eigenschaft  sein,  wenn  in  alien  Verbin- 
dungen  die  Jonen  sich  samtlich  oder  mit  einem  [949]  kon- 
stanten  Bruchteil  an  der  Leitung  beteiligen.  Nach  der  Theo- 
rie  von  Arrhenius  ist  dieses  nicht  der  Fall.  Die  Elektrizitats- 
leitung  wird  nur  von  den  aktiven  Molekeln  iibernommen; 
der  Aktivitatskoeffizient,  d.  h.  das  Verhaltnis  der  leitenden 
zu  den  insgesamt  vorhandenen  Molekeln  variiert  nicht  nur 
bei  den  verschiedenen  Verbindungen,  sondern  er  ist  auch  bei 
derselben  Verbindung  von  der  Konzentration  abhangig, 
dergestalt,  dass  er  mit  der  Verdunnung  wachst  und  bei 
grosser  Verdunnung  dem  Grenzwerte  1  zustrebt.  Kohl- 
rauschs  Gesetz  erlangt  daher  hiernach  im  allgemeinen  erst 
bei  sehr  kleinen  Konzentrationen  strenge  Giiltigkeit.  Die 
gute  Uebereinstimmung,  welche  man  1.  c.  S.  215  :  findet, 
riihrt  daher,  dass  die  daselbst  aufgefiihrten  Verbindungen  bei, 
der  Konzentration  f0  normal,  auf  welche  sich  die  Leitungs- 
vermogen  und  Ueberfiihrungszahlen  beziehen,  einen  nahe 
gleichen  Aktivitatskoeffizienten,  etwa  0.88,  besitzen.  Uebri- 
gens  sei  darauf  hinge wiesen,  dass  auch  Herr  Kohlrausch 
selber 2  seinem  Gesetze  eine  naherungsweise  Giiltigkeit 
zuschrieb  und  eine  Untersuchung  zur  Prlifung  desselben  bei 
grossen  Verdlinnungen  fur  wiinschenswert  hielt.  Eine  neuere 
Untersuchung  von  Herrn  Ostwald,3  in  der  die  Leitvermogen 
einer  grossen  Anzahl  Elektrolyte  bis  zu  sehr  bedeutenden 
Verdtinnungen  untersucht  wurden,  hat  bereits  ein  diesen 
Anschauungen  gunstiges  Resultat  geliefert. 

Den  physikalischen  Unterschiede  zwischen  den  aktiven 
und  inaktiven  Molekeln  hat  Herr  Arrhenius  bekanntlich 
in  Weiterfiihrung  der  Clausius-Williamsonschen  Hypothese 
darin  gefunden,  dass  jene  in  ihre  mit  gleich  grosser  aber  ent- 
gegengesetzter  Elektrizitat  geladene  Jonen  dissociiert  sind, 

1  Kohlrausch,  Wied.  Annalen,  26,  215  (1885).  J  Loc.  cit.  S.  216  (1885). 

8  Ostwald,  Zeitschr.  1,  61  und  97  (1887). 


KINETIK  DER  GELOSTEN  KORPER    253 

wahrend  bei  letzteren  der  elektropositive  und  negative  Be- 
standteil  in  ihrem  Bewegungszustande  nicht  von  einander 
unabhangig  sind. 

Urn  nun  Kohlrauschs  Gesetz  von  diesen  veranderten  Ge- 
sichtspunkten  aus  zu  prlifen,  fehlt  es  vor  allem  an  geniigen- 
den  Untersuchungen  der  Ueberf  iihrung,  woriiber  in  anbetracht 
der  Wichtigkeit,  welche  die  genaue  Kenntnis  dieses  Phano- 
mens  f lir  die  Mechanik  der  Elektrolyse  und  die  Konstitution 
der  Losungen  besitzt,  Uberraschend  wenige  Arbeiten  vorlie- 
gen.  Seit  den  klassischen  Untersuchungen  von  Herrn  Hit- 
torf  1  haben  nur  vereinzelt  Forscher  2  Messungen  hieriiber 
angestellt.  In  der  Absicht,  zur  Ausf tillung  dieser  Liicke  in  der 
Wissenschaft  beizutragen  und  eine  Priifung  obigen  Gesetzes 
an  sehr  verdiinnten  Losungen  zu  ermoglichen,  haben  wir  an 
einer  Anzahl  Saureradikale,  hauptsachlich  organischer  Na- 
tur  [950],  durch,  gleichzeitige  Messungen  der  Ueberf  iihrung 
und  der  Leitfahigkeit  von  Silbersalzen  die  Jonenbeweglich- 
keiten  zu  ermitteln  gesucht,  deren  Kenntniss,  wie  einer  von 
uns  zu  zeigen  gesucht  hat,  auch  fur  andere  Phanomene  von 
Wichtigkeit  zu  sein  scheint.3  Auch  haben  wir  einige  Bestim- 
mungen  ausgefiihrt,  welche  liber  die  Frage  nach  dem  Einfluss 
der  Temperatur 4  auf  die  Wanderungsgeschwindigkeiten 
orientieren  soil  ten. 

Fur  die  Wahl  des  Silbers  als  positives  Jon  sprachen  eine 
Anzahl  Griinde;  zur  Bestimmung  des  Grenzwertes  desmole- 
kularen  Leitvermogens  empfahl  sich  im  Interesse  der  gros- 
seren  Sicherheit  ein  einwertiges  Jon,  und  Silber  ist  das  ein- 
zige  einwertige  Metall,  welches  sich  —  ein  grosser  Vorteil  bei 

1  Hittorf,  Pogg.  Annalen,  89,  177.   98,  1.   103,  1.  106,  337. 

1  G.  Wiedemann,  Pogg.  Annalen,  99,  177.  Kirmis,  Wied.  'Annalen,  4,  503. 
Weiske,  Pogg.  Annalen,  103,  466.  Kuschel,  Wied.  Annalen,  13,  289.  Lenz,  Mem. 
de  St.  Petersb.  30,  1882. 

•  Nernst,  Zeitschr.  2,  613  (1888). 

4  Nernst,  Ibid.  623  (1888). 


254  MORRIS  LOEB 

derartigen  Messungen  —  bequem  als  Elektrode  verwenden 
lasst.  Seine  Salze  sind  leicht  in  geniigender  Reinheit  zu 
beschaffen.  Sodann  bot  sich  uns  in  der  eleganten  Titrier- 
methode  auf  Silber  von  Herrn  Volhard 1  die  Moglichkeit,  die 
notigen  Analysen  mit  grosser  Leichtigkeit  und  durchaus 
geniigender  Sicherheit  auszufuhren. 

2.  APPARAT   ZUR   BESTIMMUNG   DER   UEBERFUHRUNGS- 

ZAHL 

Bei  der  Wahl  desselben  suchten  wir  die  Anwendung  von 
Membranen  zu  umgehen,  um  storende  Nebenwirkungen 
vollig  zu  vermeiden,  und  waren  darauf  bedacht,  seinen  innern 
Widerstand  moglichst  gering  zu  machen,  damit  bei  den  sehr 
verdiinnten  Losungen,  mit  denen  wir  arbeiteten,  die  Zeit- 
dauer  eines  Versuchs  nicht  iibermassig  sich  ausdehne.  Wir 
sind  schliesslich  nach  mehreren  Versuchenbei  einemApparate 
stehen  geblieben,  welcher  bei  seiner  Einf  achheit  sich  in  vielen 
Fallen  als  brauchbar  erweisen  diirfte.  Er  besitzt  im  wesent- 
lichen  die  Form  einer  Gay-Lussacschen  Burette  und  ist  in 
nebenstehender  Zeichnung  dargestellt.  Um  das  lastige  Her- 
abfallen  des  an  der  Kathode  sich  niederschlagenden  Silbers 
zu  vermeiden,  ist  ein  seitliches  Ansatzrohr  —  von  derselben 
Weite  wie  das  Hauptrohr  —  angeschmolzen,  welches  in  einer 
Kugel  endigt,  die  zur  Aufnahme  der  Kathode  dient  [951], 
Eingefiihrt  wird  dieselbe  durch  das  engere  Rohr  B;  sie 
besteht  aus  einem  an  einem  Silberdraht  befestigten  und 
cylindrisch  gerollten  Silberblech.  Die  Anode,  ein  an  seinem 
untern  Ende  spiralformig  gewickelter  Silberdraht,  wird  durch 
A  eingefiihrt  und  reicht  bis  auf  den  Boden  des  Gefasses.  Um 
den  Eintritt  des  Stromes  in  die  Losung  nur  am  unteren  Ende 
zu  ermoglichen,  ist  der  gerade  Teil  des  Drahtes  mit  einer 
diinnwandigen  Glaskapillare  iiberzogen,  die  sich  trotz  des 

1  J.  Volhard,  Annalen,  190,  1  (1878).  , 


KINETIK  DER  GELOSTEN  KORPER     255 


verschiedenen  Ausdehnungskoeffizienten  von  Silber  und  Glas 

gut  an  den  Draht  anschmelzen  liess.   Die  Oeffnungen  A  und 

B  tragen  durchbohrte,  von  kurzen 

Glasrohrchen  durchsetzte  Korke. 

Das  Rohrchen  bei  A  lasst  den  Elek- 

trodendraht    einfach    hindurch- 

gehen,  wahrend  dasjenige  bei  B 

einen   seitlich   eingeschmolzenen 

Platindraht  besitzt,  an  welchem 

die  Elektrode  aufgehangt  wird. 

Es  kann  so  A  durch  ein   iiber 

Draht  und  Rohrchen  gezogenes 

Endchen  Gummischlauch  mittelst 

Quetschhahn  verschlossen,  bei  B 

mittelst    eines    Gummischlauchs 

gesaugt    oder   geblasen    werden, 

ohne  die  Elektroden  zu  erschiittern. 

Bei  Ausfiihrung  eines  Versuchs  wurde  nun  ein  solcher 
Apparat  samt  Elektroden  und  Korken,  aber  ohne  die  Gum- 
miverbindungen,  gewogen;  A  alsdann  in  erwahnter  Weise 
geschlossen  und  bei  B  gesaugt,  wahrend  die  Miindung  von 
C  unter  die  Oberflache  der  betreffenden  Losung  tauchte.  Der 
Apparat  fiillte  sich  so  bis  zur  Hohe  der  oberen  Wand  des  An- 
satzrohrs  und  enthielt,  je  nach  Grosse,  40  oder  60  cc.  Losung. 
Nunmehr  wurde  das  Ausflussrohr  ebenfalls  durch  ein  Gum- 
mikappchen  verschlossen,  der  Apparat  aufrecht  in  einen 
Wasserthermostaten  nach  Herrn  Ostwald  1  gehangt  und, 
nachdem  die  Temperatur  sich  ausgeglichen  hatte,  die  Strom- 
leitung  angelegt.  Sofort  nach  Beendigung  der  Elektrolyse 
wurde  das  Ausflussrohr  geoffnet  und  durch  Anblasen  bei  B 
beliebige  Teile  der  Losung  in  tarierte  Gef asse  gefiillt,  gewogen 
und  analysiert.  Die  Menge  der  im  Apparate  verbleibenden 

1  Ostwald,  Zeitschr.  2,  565  (1888). 


£56  MORRIS  LOEB 

Losung  wurde  durch  die  Gewichtszunahme  desselben  be- 
stimmt.  Wenn  nun  wahrend  des  Versuchs  keine  Mischung 
durch  Diffusions-  oder  Konvektionsstrome  stattgefunden 
hat,  so  wird  bei  passender  Einteilung  die  zuerst  auslaufende 
Schicht  die  konzentriertere  Losung  an  der  Anode,  sowie 
gentigende  Menge  unveranderte  Losung  enthalten,  um  voll- 
standig  nachzuspiilen.  Die  folgenden  Schichten  miissen  eine 
unveranderte  Konzentration  zeigen,  wahrend  der  im  Apparat 
zuriickbleibende  Anteil  die  verdiinnte  Losung  um  die  Kathode 
enthalt.  Die  Probe  dafiir,  dass  der  Versuch  brauchbar  war, 
lag  also  sowohl  in  dem  Unverandertsein  der  mittleren  Schich- 
ten, wie  darin,  dass  die  Losung  um  die  Kathode  ebensoviel 
[952]  Silber  verloren  hatte,  als  diejenige  um  die  Anode  mehr 
enthielt.  Nachdem  wir  die  erste  Bedingung  stets  erfiillt 
gefunden  hatten,  verzichteten  wir  schliesslich  imlnteresse  der 
schnelleren  Ausflihrung  der  Versuche  auf  die  Entnahme  der 
mittleren  Schichten  und  begnligten  uns,  die  Losung  in  zwei 
etwa  gleiche  Portionen  zu  teilen.  Wenn,  wie  es  haufig  vorkam, 
ein  Wachsen  des  niedergeschlagenen  Silbers  von  der  Kugel 
aus  das  Ansatzrohr  entlang  stattfand,  so  wurde  der  Versuch 
unterbrochen,  ehe  das  Hauptrohr  erreicht  war. 

Die  Analysen  wurden,  wie  oben  erwahnt,  mittels  Titra- 
tion  durch  Rhodanammoniumlosung  ausgefiihrt,  deren  Ge- 
halt  (etwa  ^  normal)  durch  of tmaligen  Vergleich  mit  einer 
Silbernitratlosung  ermittelt  wurde.  Der  Titer  der  letzteren 
wurde  im  Laufe  der  Untersuchungen  mehrmals  gewichts- 
analytisch  bestimmt  und  stets  unverandert  gefunden.  Die 
Titrationen  konnen  eine  Genauigkeit  bis  auf  gut  §5  cc.[ =0-038 
mg  Ag]  beanspruchen,  besonders  da  zur  Kontrolle  der  Farben- 
umschlag  stets  doppelt  beobachtet  wurde;  es  wurde  namlich 
nach  Eintreten  der  ersten  Farbung  noch  aus  einer  Pipette 
1  cc.  i^o  AgNO3  Losung  zugeftigt  und  wiederum  der  Farben- 
umschlag  beobachtet. 


KINETIK  DER  GELOSTEN  KORPER    257 

In  die  TJeberfiihrungszahl  geht  ausser  der  Menge  des  iiber- 
fiihrten  noch  die  des  gleichzeitig  ausgeschiedenen  Silbers 
ein,  zu  deren  Bestimmung  man  sich  bekanntlich  am  einfach- 
sten  eines  in  den  Stromkreis  eingeschalteten  Silbervolt- 
ameters  bedient.  Da  dieselbe  aber  haufig  bei  der  Unter- 
suchung  verdiinnter  Losungen  weniger  als  20  mg  betrug, 
eine  so  geringe  Quantitat  bei  dem  schwer  vollig  zu  vermei- 
denden  Verlust  kleiner  Silberflitterchen  sich  nicht  mit  einer 
geniigenden  Genauigkeit  bestimmen  lasst,  so  haben  wir  die 
Elektrizitatsmenge,  welche  wahrend  der  Elektrolyse  den 
Apparat  durchfloss,  durch  galvanometrische  Messung  ermit- 
telt.  In  den  Stromkreis  (s.  Fig.)  wurde  ein  Stopselrheostat 
eingeschaltet,  an  dessen  Enden  sich  ein  Nebenkreis  an- 
schloss,  welcher  ein  Galvanometer  mit  direkter  Ablesung  und 
ein  Clark-Element  enthielt.  Durch  richtige  Wahl  des  aus 
dem  Rheostaten  eingeschalteten  Widerstandes  W,  sowie 
passende  Schaltung  des  Elements,  kann  bekanntlich  stets 
das  Galvanometer  stromlos  gemacht  werden;  dann  ist  die 

ri 

Intensitat  im  Hauptkreis  i=yy>  wo  E  die  elektromotorische 

Kraft  des  Normalelementes  bedeutet.  Da  wahrend  der 
Dauer  der  Elektrolyse,  gewohnlich  4  bis  5  Stunden,  die 
Stromintensitat  sich  wenig  und  zwar  ausserordentlich  stetig 
sich  anderte,  so  geniigte  es,  eine  derartige  Strommessung, 
welche  sich  in  wenigen  Sekunden  ausfiihren  Hess,  alle  zehn 
Minuten  vorzunehmen,  um  das  Stromintegral  mit  weitaus 
geniigender  Sicherheit  in  der  bekannten  Weise  zu  berechnen. 
[953]  Durch  besondere  Versuche  ergab  sich,  dass,  wenn 
Widerstandskasten  und  Element  eine  Temperatur  von  18° 
besassen,  die  ausgeschiedene  Silbermenge/  sich  aus  der  Formel 

/=  96-29- 
w 


258  MORRIS  LOEB 

berechnen  lasst;  hier  bedeutet  z  die  Zeitdauer  der  Elektrolyse 
in  Minuten,  und  w  den  berechneten  Widerstand,  der,  wenn 
wahrend  dieser  Zeit  die  gleiche  Elektrizitatsmenge  in  kon- 
stantem  Strome  den  Apparat  durchflossen  hatte,  eingeschaltet 
werden  miisste,  um  das  Galvanometer  stromlos  zu  machen. 
Betrug  die  Temperatur  von  Element  und  Kasten  t,  so  war 
obige  Zahlmit  1-0.0012  (2—18)  zu  multiplizieren,  wobei  sich 
der  Temperaturkoeffizient  0.0012  aus  dem  des  Elements, 
—0.0008,  und  dem  des  Kastens,  +0.0004,  zusammensetzt. 

Aus  der  Thatsache,  dass  nach  Herrn  Kohlrausch  l  ein 
Amper  per  Sekunde  1.118  mg  Ag  zersetzt,  und  der  Angabe, 
dass  die  Einheit  unseres  Kastens  das  legale  Ohm  war,  ergiebt 
sich  (die  absolute  Widerstandseinheit  =  1.063  SE  gesetzt) 
die  elektromotorische  Kraft  unseres  Clark-Elementes  bei 
18°  zu  1.431  Volt.  Die  Zahl  stimmt  gut  mit  den  Angaben 
der  Herren  Lord  Rayleigh  (1.434  bei  15°)  und  v.  Ettings- 
hausen  2  (1.433  bei  13.5°).  Auf  18°  umgerechnet,  geben  letz- 
tere  Werte  1.431  und  1.428,  und  beweist  die  Uebereinstim- 
mung  unserer  Zahl  mit  diesen,  dass  wir  in  der  That  im  Clark- 
Element  einen  Etalon  fiir  eine  elektromotorische  Kraft  be- 
sitzen,  bei  dessen  Anwendung  man  Fehler  iiber  2  pro  mille 
kaum  wird  begehen  konnen. 

Als  Stromquelle  dienten  uns  38  Leclanche-Elemente, 
deren  elektromotorische  Kraft  zusammen  etwa  40  Volt 
betrug  und  welche  einen  innern  Widerstand  von  etwa  120 
Ohm  besassen.  Um  das  Auswachsen  des  Salmiaks  zu  ver- 
meiden,  waren  die  oberen  Rander  der  Batterieglaser  und  der 
Kohlenstabe  mit  Paraffin  iiberstrichen.  In  einen  Widerstand 
von  5  bis  10000  Ohm  geschlossen,  liefert  die  Batterie  Stunden 
lang  einen  durchaus  konstanten  Strom  und  bietet  dieselbe 
ausserdem  den  Vorteil,  stets  zum  Gebrauch  bereit  zu  sein. 

1  F.  Kohlrausch,  Leitf.  d.  prakt.  Physik,  327  (1887). 

2  Wiedemann,  Elektrizitat,  4,  985  (1885).  j 


KINETIK  DER  GELOSTEN  KORPER    259 


3.  DABSTELLUNG  DER  LOSUNGEN  l 

Die  Losung  von  Silbernitrat  (AgNO3)  wurde  durch  Auf- 
losung  des  krystallisierten  Salzes  erhalten.  Die  Silbersalze 
der  Chlorsaure  (AgClO3),  [954]  Ueberchlorsaure  (AgClO4), 
Aethylschwefelsaure  (AgO4SC2H5),  Naphthalinsulfonsaure 
(AgO3SCioH7),  Benzolsulfonsaure  (AgO3SC6H5),  Pseudo- 
kumolsulfonsaure  (AgOsSCgHn),  Essigsaure  (AgO2C2H3) 
wurden  durch  Abstumpfung  der  freien  Sauren  mit  feuchtem 
Silberoxyd  und  nachheriges  Filtriern  durch  Asbest  darge- 
stellt.  Dithionsaures  Silber  (Ag2S2O6)  wurde  durch  Wech- 
selzersetzung  aquivalenter  Mengen  Baryumdithionat  und 
Silbersulfat  gewonnen.  Um  Kieselfluorsilber  (Ag2SiFl6) 
zu  erhalten,  wurde  in  eine  Losung  von  Fluorkieselsaure  so 
viel  Silberoxyd  eingetragen,  als  dieselbe  aufnehmen  wollte; 
darauf  wurde  so  lange  Baryumhydratlosung  zugetropfelt, 
bis  sich  zu  dem  niederfallenden  Baryumfluorsilikat  etwas 
braunes  Silberoxyd  gesellte.  Die  neutrale  Losung  wurde 
filtriert  und  auf  die  gewiinschte  Verdlinnung  gebracht. 

4.  AUSFUHRLICHE  MlTTEILUNG  EINES  VERSUCHS  ALS 
BEISPIEL 

Derselbe  wurde  bei  einer  Temperatur  von  26°  mit  etwa 
i^o  normaler  Silbernitratlosung  ausgefiihrt,  welche  nach  Be- 
endigung  der  Elektrolyse  in  vier  Schichten  geteilt  wurde. 
In  der  folgenden  Tabelle  befindet  sich  unter  I  die  Gewichts- 
menge  der  Schichten,  unter  II  die  darin  gefundene  Menge 
Silber,  unter  III  die  Silbermenge,  welche  darin  ohne  Elek- 
trolyse enthalten  gewesen  ware  und  sich  aus  der  Angabe 
berechnet,  dass  1  g  Losung  1.139  mg  Ag  enthielt. 

1  Dieselbe  1st  von  M.  Loeb  ausgefiihrt. 


260  MORRIS  LOEB 


TAB.  1. 

Nr. 

I 

II 

III 

Diff. 

1 
2 

20-09  g 

5-27 

39  •  66  mg 
5-96 

22-88mg 
6-00 

+16.78 
-0-04 

3 

5-38 

6-04 

6-07 

-0-03 

4 

27-12 

14-14 

30-89 

-16-75 

57-81  65-80 

Wie  man  sieht,  1st  der  Gehalt  der  beiden  mittleren  Schichten 
2  und  3  innerhalb  der  Analysenf ehler  unverandert  geblieben; 
auch  das  zweite  Kriterium  fiir  die  Brauchbarkeit  des  Ver- 
suchs,'dass  namlich  der  aus  dem  Versuche  berechnete  von 
dem  direkt  gefundenen  Gehalt  nicht  differiert,  sehen  wir  sehr 

ftfr  Of\ 

nahe  erfullt,  indem  aus  -      -  =1.138  ein  demob igen  direkt 

57.81 

bestimmten  1.139  nahe  kommender  Wert  sich  ergiebt. 

Aus  der  Strommessung  in  der  angegebenen  Weise  berechnete 
sich  die  der  durch  den  Apparat  geflossenen  Elektricitats- 
menge  aquivalente  Silbermenge  zu  32.10  mg,  wahrend  in 
einem  zur  Kontrolle  gleichzeitig  eingeschalteten  [955]  Silber- 
voltameter  32.2  mg  sich  vorfanden;  der  erstere  Wert,  als 
der  zuverlassigere,  wurde  angenommen. 

Die  Ueberf iihrungszahl  ist  aus  obigen  Daten  nach  Hittorf x 
folgendermassen  zu  berechnen.  In  die  Losung  um  die  Anode 
(1)  sind  32.1  mg  Ag  ein,  aus  der  um  die  Kathode  (4)  ebenso- 
viel  ausgetreten.  Vor  der  Elektrolyse  fiihrten(l  -0.0011390)  g 
Wasser  1.139  mg  Ag,  wo  v  das  Vernal tnis  des  Molekular- 
gewichts  des  Silbernitrats  zu  dem  Atomgewicht  des  Silbers, 

170 

——  =  1.57,  bedeutet.    Nach  der  Elektrolyse  waren  an  der 

108 

Anode  (20.09-0.03966  v)  g  Wasser  mit  39.66  mg  Ag,  an  der 
Kathode  (27.12-0.01414  v)  g  Wasser  mit  14.14  mg  Ag  ver- 

*  Pogg.  Annalen,  98,  19  (1856). 


KINETIK  DER  GELOSTEN  KORPER    261 

bunden.    Die  Lfisung  um  die  Anode  ist  somit  um  39.66- 
(20.09-0  03966  .) 


^07  i  o_o 
mg  Ag  reicher,  diejenige  um  die  Kathode  un 


1-0.001139  v 

1.139-16.82  =  (27.12Xll.39-16.82)  (1+0.001139  v)  mg  Ag 
armer  geworden,  indem  das  kleine  Defizit  der  mittleren 
Schichten  zu  dem  Mindergehalt  von  Nr.  4  hinzugefiigt  ist. 
Wie  man  sieht,  geben  die  in  Tabelle  1  angefiihrten  Differen- 
zen,  welche  den  ersten  Faktoren  der  beiden  obigen  Produkte 
entsprechen,  nicht  genau  die  Menge  der  Zu-  resp.  Abnahme 
von  Ag  an,  sondern  sind  mit  einem  Korrektionsglied  be- 
haftet,  welches  jedoch  fiir  Losungen  so  geringer  Konzentra- 
tion  sehr  klein  ist.  Die  Ueberfiihrungszahl,  bezogen  auf  das 
Anion  NO3,  folgt  also  zu 

1.0017,  resp.  ^^  1.0017,  im  Mittel  0.524. 


32.10  32.10 

Nachdem  wir  wiederholt  ein  ahnlich  giinstiges  Resultat 
betreffs  des  Unverandertseins  der  mittleren  Schichten  ge- 
funden  batten,  wurde,  wie  schon  erwahnt,  schliesslich  die 
Losung  aus  dem  Apparate  meistens  in  nur  zwei  Portionen 
geteilt  untersucht. 

Da  bei  dem  eben  mitgeteilten  Versuch  in  den  Stromkreis 
gleichzeitig  noch  ein  zweiter  Apparat  eingeschaltet  war,  so 
betrug  die  mittlere  Stromintensitat  nur  etwa  0.0012  Amper, 
die  Versuchsdauer  7  Stunden.  Im  Interesse  des  sehnelleren 
Arbeitens  und  um  die  Batterie  mehr  auszunutzen,  zogen  wir 
es  in  den  meisten  Fallen  vor,  zwei  Apparate  neben  einander 
zu  schalten,  wo  dann  natiirlich  jeder  der  beiden  Hauptkreise 
behufs  Strommessung  einen  eigenen  Rheostaten  enthielt; 
durch  eine  geeignete  Schaltung  wurde  dann  der  Nebenkreis 
bald  an  den  einen,  bald  an  den  anderen  [956]  Widerstands- 
kasten  angelegt,  und  so  in  jedem  Kreise  der  Strom  gemessen; 


MORRIS  LOEB 

bei  der  so  erzielten  doppelten  Intensitat  sank  die  Versuchs- 
dauer  auf  3  bis  4  Stunden.  Es  sei  noch  erwahnt,  dass  wir,  um 
ganz  sicher  zu  gehen,  das  benutzte  Clark-Element  haufig  mit 
einem  zweiten  verglichen;  die  absolute  Gleichheit  der  elektro- 
motorischen  Krafte  beider  lehrte,  dass  sich  das  benutzte 
Element  nicht  wahrend  der  Versuche  anderte. 

5.  MESSUNGEN  DER  UEBERFUHRUNGSZAHL 

Im  folgenden  bedeutet  t  die  Versuchstemperatur;  m  den 
Molekulargehalt  der  Losung  (Grammaquivalente  pro  Liter) ; 
/i  die  aus  der  Strommessung  berechnete  Silbermenge  in  Milli- 
grammen,  welche  sich  im  Apparat  wahrend  des  Versuchs 
ausschied;/2  dieselbe  Grosse,  wiesie  sich  im  Silbervoltameter, 
welches  oft  gleichzeitig  eingeschaltet,  vorfand;  n  die  Ueber- 
fiihrungszahl,  bezogen  auf  das  Anion.  Dem  Werte  von  n  ist 
stets  derjenige  fur  f\  zu  Grunde  gelegt. 

Salpetersaures  Silber 

1)2  =  20°.  m  =  0-1043.  /  =  83'5.  /.  =  83'6.     n  =  0'528. 

2)*  =  26°.  m  =  0-0521.  /!  =  76-7.  7i  =  0'524. 

3)2  =  26°  m  =  0-025.  /t  =  48'0.  n  =  0'5223. 

4)^  =  0°.  7/1  =  0-025.  /t  =  48-0.  n  =  0-5383. 

5)2  =  26°.  m  =  0-0105.  /1  =  32'10.  /,  =  32-2.     n  =  0-524. 

6)2  =  26°.  m  =  0-0105.  /t  =  32'10.  /,  =  322.     n  =  0'521. 

Bei  3)  und  4),  sowie  bei  5)  und  6)  waren  die  Apparate  in 
denselben  Stromkreis  gleichzeitig  eingeschaltet. 

Chlorsaures  Silber 

1)  2  =  24-8°.     w  =  0-0245.    /.=39-88.    /2=39'5.     ?i  =  0-503. 

2)  t  =  24-8°.     m  =  0-0245.    /j  =  51'72.  n  =  0'499. 

Ueherchlorsaures  Silber 

1)^  =  24-8°.    w  =  0-0247.    /.  =  89-88.    /2  =  39'5.     n  =  0'515. 
2)  t  =  24-8°.    m  =  0-0247.    f,  =  51'72.  n  =  0-512. 

Bei  der  Untersuchung  dieser  beiden  Losungen  befand  sich 
1)  mit  1)  und  2)  mit  2)  je  im  gleichen  Stromkreis. 

AetJiylschwefelsaures  Silber 

1)  t  =  24-8°.     m  =  0-0243.    /,  =  53-30.  n  =  0-385. 

2)  t  =  24-8°.    m  =  0-0243.    f,  =  48'47.  /2  =  48'34.   n  =  0-389. 
3)2  =  25-0°.    m  =  0-00606. /t  =  18- 10.  n  =  0-384. 


KINETIK  DER  GELOSTEN  KORPER     263 

NapJithalinsulfonsauret  Silber 

1)  t  =  29-2°.    m  =  0-01292.  /.  =  33'95.  n  =  0-390. 

2)*  =  25-0°.    m  =  0-0250.    ^  =  39-75.    /2  =  39'5.     n  =  0'386. 

[957]  Benzolsulfonsaures  Silber 

1)  t  =  24-8°.    m  =  0-0250.    /,  =  48-47.   /,  =  48'34.    n  =  0-343. 

2)  £  =  24'7°.     m  =  0-0250.    /x  =  17'85.  71  =  0-351. 

Pseudokumolsulfonsaures  Silber 

1)  t  =  24-2°.  m  =  0-0238.  /.  =  61-62.  n  =  0'293. 

2)  t  =  29-2°.  m  =  0-02216.  /t  =  38'24.  n  =  0'2947. 

3)  t  =   0°.  m  =  0-02216.  /t  =  38'24.  n  =  0'2732. 

4)  *=   0°.  m  =  0-02216.  /;  =  42-79.  n  =  0-2731. 

Bei  2)  und  3)  befanden  sich  die  Apparate  im  gleichen  Strom- 
kreis. 

Essigsaures  Silber 

Bei  der  Untersuchung  dieses  Salzes  zeigten  sich  Schwierig- 
keiten,  indem  nach  Schluss  des  Versuches  die  mittelste 
Schicht  nicht  unverandert  blieb,  und  der  aus  dem  Versuch 
sich  ergebende  Titer  der  Losung  nicht  gut  mit  dem  direkt 
gefundenen  iibereinstimmte.  Es  ist  nicht  unwahrscheinlich, 
dass  diese  Unregelmassigkeiten  mit  der  geringen  Loslichkeit 
des  Salzes  zusammenhangen,  indem  sich  leicht  an  der  Anode 
die  Losung  so  konzentrieren  kann,  dass  festes  Salz  ausfallt 
und  sich  im  Laufe  des  Versuchs  zersetzt.  Schliesslich  gelang 
es,  mit  sehr  verdlinnter  Losung  anscheinend  brauchbare 
Resultate  zu  erhalten. 

1)  *  =  25°.     m  =  0-00972.    f,  =  20'80.     n  =  0'375. 

2)  t  =  24°.     m  =  0-00972.    /t  =  23'99.    n  =  0'377. 

Von  Salzen  zweibasischer  Sauren  wurden  untersucht:  — 

Dithionsaures  Silber 

1)^  =  24-8°.  m  —  0-0246.  /t  =  33'40.  n  =  0*604. 

2)  t  =  29-2°.  m  =  0-0246.  /,  =  46'70.  n  =  0'604. 

8)*=    0°.  m  =  0-0246.  /1  =  46'70.  n  =  0'605. 

4)^  =  24-2°.  m  =  0-0246.  /t=48-85.  n  =  0'606. 

5)  t  =    0°.  m  =  0-0246.  /j  =  45'80.  n  =  0'603. 

Bei  2)  und  3)  waren  die  Apparate  im  gleichen  Stromkreis 
hintereinander  geschaltet. 


264  MORRIS  LOEB 


Kieselfluorsilber 

1)  £  =  22  2°.     771  =  0-02815.    /x  =  60'28.     n  =  0'467. 

2)  £  =  22-2°.     w  =  0-02815.     /x  =  37'44.     n  =  0'464. 

In  Tabelle  2  sind  die  gewonnenen  Resultate  der  Ueber- 
fiihrungszahlen  n  nebst  den  dazugehorigen  Temperaturen 
und  Konzentrationen  zusammengestellt  : 

[958]  TAB.  2. 

n  t  m 

Salpetersaures  Silber        0-523  25°        n1     n  n1 

0-539  0° 

Chlorsaures     "  0'505  25°        0*0245 

Ueberchlorsaures  0'514  25°        0'0247 

Aethylschwefelsaures     "  0-385  25°        0  •  0243—  0  •  0061 

Naphthalinsulfonsaures     "  0'390  30° 

0-386  25° 

Pseudokumolsulfonsaures     "  0-293  25°        A.AOQ 

0-273  0° 

Benzolsulfonsaures     "  0-347  25°        0-025 

Essigsaures     "  0-376  25°        0"0097 


Dithionsaures  0'604  25° 

0-604  0° 


0-0246 


Kieselfluorwasserstoffsaures  0'466  22°        0*0282 

Salpetersaures  Silber  ist  eingehend  bereits  von  Herrn  Hittorf 1 
untersucht  worden,  welcher  etwa  vom  Gehalte  0.3  ab warts 
bis  0.024  die  Ueberfiihrungszahl  ungeandert,  im  Mittel 
0.526  bei  19°  fand.  Wir  finden  das  gleiche  Ergebnis  bei  Varia- 
tion des  Titers  von  0.1-0.01  und  einen  dem  Hittorfschen 
sehr  nahen  Wert,  namlich  0.527  auf  die  gleiche  Temperatur 
umgerechnet.  Audi  obiger  Wert  fiir  Silberacetat  stimmt  gut 
mit  dem  Hittorfschen  (0.373  bei  2  =  15°  und  m=0.05). 

6.  LEITVERMOGEN  DER  SILBERSALZE  2 

Dasselbe  wurde  bei  25°  nach  der  Kohlrauschschen  Methode 
mittelst  Telephon  und  Messbriicke  bestimmt.  Die  Losungen 
vom  Gehalte  m= 0.025 -0.01  wurden  in  einem  vom  Wasser- 
bade  eines  Thermostaten  umgebenen  Widerstandsgefass 

1  Pogg.  Annden,  89,  199  (1853). 

2  Diese  Messungen  sind  von  W.  Nernst  ausgefiilirt. 


KINETIK  DER  GELOSTEN  KORPER    265 


nach  Herrn  Arrhenius  l  untersucht  und  durch  wiederholtes 
Verdiinnen  auf  die  Halfte,  wie  von  Herrn  Ostwald  beschrie- 
ben,  bis  auf  etwa  0.0008  gebracht.  Die  unten  mitgeteilten 
Zahlen  beziehen  sich  auf  das  Leitungsvermogen  von  Queck- 
silber  =  l,  indem  die  von  Herrn  Kohlrausch  bei  18°  fur  Silber- 
nitrat  beobachteten  Leitvermogen 2  der  Berechnung  zu 
Grunde  liegen.  Zur  grosseren  Sicherheit  der  Umrechnung 
wurde  zwischen  18°  und  25°  der  Temperaturkoeffizient  bei 
den  Gehalten  m=0.1,  0.02,  0.005  bestimmt  und  zu  0.0213, 
0.0217,  0.0222  gefunden.  Der  Wert  von  Herrn  Kohlrausch,3 
0.0221  bei  m=0.01,  schliesst  sich  gut  an.  In  der  folgenden 
Tabelle  befinden  sich  [959]  die  mittelst  dieser  resp.  inter- 
polierter  Temperaturkoeffizienten  auf  25°  nach  den  Zahlen 
von  Herrn  Kohlrausch  4  umgerechneten  und  die  von  uns  bei 
dieser  Tempera  tur  durch  fortgesetztes  Verdiinnen  gefun- 
denen  Werte  fur  das  Leitungsvermogen  von  Silbernitrat. 

TAB.  3 


XX  108 

XX  108 

m 

K. 

L.  u.  N. 

m 

K. 

L.  u.  N. 

o-i 

1018 

1022 

0-007 

1178 

1188 

0-05 

1071 

1086 

0-003 

1211 

1206 

0-025 

1128 

1126 

0-0015 

1226 

1221 

0-015 

1158 

1153 

0-0008 

1234 

1232 

Der  Parallelismus  zwischen  beiden  Zahlenreihen  ist  befriedi- 
gend.  Fur  die  iibrigen  Salze  fanden  wir  folgende  Werte, 
wobei  der  Molekulargehalt  m  (g-Aequivalente  pro  Liter) 
durch  Bestimmung  der  (von  eins  wenig  verschiedenen) 
spezifischen  Gewichte  bei  18°  aus  der  analytischen  Bestim- 
mung des  Gehaltes  in  Gewichtsprozenten  auf  diese  Tempera- 

1  Zeitschr.  2,  563  (1888). 

2  Unter  "Leitvermogen"  schlechthin  sei  hier  "molekulares  LeitungsvermSgen" 


verstanden. 
1  Wied.  Annalen.  26,  223  (1885). 


*  Ibid.  195  (1885). 


266 


MORRIS  LOEB 


tur  umgerechnet  1st.  Die  Korrektion  wegen  des  Leitungs- 
vermogens des  zum  Verdiinnen  benutzten  Wassers,  welches 
2.5X10"10  betrug,  1st  in  bekannter  Weise  angebracht  worden. 
Die  -wegen  Kontraktion  der  Losungen  beim  Verdiinnen 
anzubringenden  Korrekturen  sind  verschwindend. 

TAB.  4 


XX  108 

771 

AgC103 

AgC104 

Ag04SC2H5 

Ag03SC10H7 

Ag03SC8H5 

0-025 

1045 

1109 

_ 

0-015 

1103 

1139 

— 

882 

846 

0-007 

1123 

1160 

905 

893 

874 

0-003 

1151 

1182 

930 

926 

897 

0-0015 

1160 

1194 

943 

941 

900 

0-0008 

1163 

1200 

949 

951 

906 

TAB.  4  (FOKTSETZUNG) 


m 

AgO,SC,Hn 

XX  108 
Ag02C2H3 

iAg2S206 

iAg2SiFlfl 

0-025 

734 

_ 

1253 

995 

0-015 

762 

— 

1343 

1020 

0-007 

791 

897 

1383 

1054 

0-003 

813 

926 

1442 

1081 

0-0015 

826 

944 

1474 

1096 

0-0008 

836 

949 

1505 

1100 

[960]  Die  von  Herrn  Ostwald l  an  zahlreichen  einbasischen 
Natriumsalzen  beobachtete  Regelmassigkeit  eines  sehr  nahe 
gleichen  Aktivitatskoeffizienten  lasst  sich  auch  leicht  an  dem 
hier  vorliegenden  Material  wiederfinden;  die  Quotienten  des 
Leitungsvermogens  eines  Salzes  bei  verschiedenem  Gehalte 
variieren  bei  den  Silberverbindungen  einbasischer  Sauren 
nur  innerhalb  der  Grenzen,  welche  die  Beobachtungsfehler 
kaum  iiberschreiten.  Von  dieser  Thatsache  soil  Gebrauch 
gemacht  werden,  um  den  Grenzwert  des  Leitungsvermogens 

1  Ostwald,  Zeitschr.  2,  847  (1888).  ' 


KINETIK  DER  GELOSTEN  KORPER    267 


bei  sehr  grosser  Verdiinnung  zu  erhalten,  well  bei  der  gering- 
sten  von  uns  untersuchten  Konzentration  0.0008  die  voll- 
standige  Dissoziation  zwar  sehr  nahe,  aber  doch  noch  nicht 
vollig  erreicht  1st.  Beachten  wir  namlich,  dass  Silbernitrat 
nach  den  Messungen  von  Herrn  Kohlrausch  beim  Gehalte 
m  =  0.0008  im  Verhaltnis  \jjSj  in  seine  Jonen  dissoziiert  1st, 
so  werden  wir  mit  ziemlicher  Genauigkeit  die  Grenzwerte  von 
X  auch  bei  den  ubrigen  einbasischen  Silbersalzen  erhalten, 
wenn  wir  die  von  uns  bei  m= 0.0008  gefundenen  Werte  um 
0.75%  erhohen. 

In  Tabelle  5  sind  die  Messungen  verzeichnet,  welche  wir 
iiber  den  Einfluss  der  Temperatur  auf  das  Leitvermogen 
ausgefiihrt  haben;  hier  wurden  an  Stelle  der  platinierten 
Platinplatten  solche  aus  Silber  als  Elektroden  im  Wider- 
standsgefass  angewendet,  wodurch  ein  sehr  deutliches  Ton- 
minimum  im  Telephon  erzielt  wurde.  X0,  \i8,  X28  bedeuten 
die  (direkt  gemessenen)  Leitvermogen  bei  den  Temperaturen 

\B 

0°,  18°  und28°;  zieht  man,  von  T— ,  1  ab  und  dividiert  durch  10, 

A18 

so  erhalt  man  die  Temperaturkoeffizienten  zwischen  18°  und 
28°,  welche  mit  den  von  Herrn  Kohlrausch  1  mitgeteilten 

X0 
direkt  vergleichbar  sind.    Ausserdem  ist  noch  T—  durch  In- 


terpolation  berechnet. 


TAB.  5 


m 

xl8 

£ 

i 

m 

\L 

fc 

x25 

AgN03 

o-i 

0-02 
0-005 

0  638 
0-638 
0-632 

1-213 
1-217 
1-222 

0-555 
0-554 
0-548 

Ag03SC6H5 
Ag02C2H3 
AgO,SC,Hu 

0-005 
0-005 
0-025 

0-607 
0-611 
0-609 

1-241 
1-237 
1-242 

0-519 
0-524 
0-521 

AgCIO, 

0-005 

0-626  1-222 

0-542 

0-006 

0-606 

1-246 

0-517 

AgC104 

Ag03SC10H7 

0-005 
0-005 

0-632 
0  615 

1-224 
1-242 

0-547 
0-526 

|Ag2S206 

0-025 
0-006 

0-631 
0-631 

1-222 
1-226 

0-547 
0-544 

1  Kohlrausch,  Wied.  Annalen,  26,  223  (1885). 


268  MORRIS  LOEB 

7.  PRUFUNG  DEE  THEORETISCHEN  BEZIEHUNG  ZWISCHEN 
LEITVERMOGEN  UND  UEBERFUHRUNGSZAHL 

Hierzu  bedarf  man  ausser  der  Kenntnis  des  Grenzwertes 
des  Leitungsvermb'gens  bei  unendlicher  Verdiinnung,  welche 
wir  uns  soeben  zu  [961]  verschaffen  gesucht  haben,  noch  der 
Ueberfiihrungszahlen  fiir  ebenfalls  sehr  geringe  Konzent- 
rationen. 

Nun  hat,  wie  schon  erwahnt,  Herr  Hittorf  bei  AgNO3 
unter  ra=0-3  n  von  dem  Gehalte  unabhangig,  und  wir  haben 
auch  an  anderen  einbasischen  Silbersalzen  dies  Resultat 
bestatigt  gefunden,  so  dass  die  von  uns  bei  ra  =  0-025-0-01 
gefundenen  Zahlen  mit  dem  gesuchten  Grenzwert  identisch 
sein  diirften.  Dieses  Resultat  leuchtet  ohne  weiteres  ein,  wenn 
man,  wie  wir  es  auf  Grund  unserer  Anschauungen  annehmen 
mlissen,  eine  Wanderung  der  inaktiven  Molekeln  fiir  aus- 
geschlossen  halt,  und  bedenkt,  dass  bei  einer  Verdiinnung 
von  0-01  auf  5550  Molekeln  H2O  erst  ein  Silberion  kommt. 
Dann  wird  sicherlich  die  Reibung,  welche  das  Jon  bei  seiner 
Fortbewegung  erfahrt,  von  der  im  reinen  Wasser  nicht  ver- 
schieden  sein.  Dass  dies  selbst  bei  einer  Konzentration  von 
m  =  0  •  3  beim  Silbernitrat  noch  der  Fall  ist,  kann  leicht  daher 
riihren,  dass  bei  zunehmendem  Salzgehalt  die  Reibung  der 
beiden  Jonen  in  gleicher  Weise  (vermutlich  verlangsamend) 
beeinflusst  wird. 

Die  Priifung  des  Gesetzes  von  Herrn  Kohlrausch  fiir  den 
Fall  sehr  grosser  Verdiinnung  lasst  sich  am  einfachsten  in 
der  Weise  bewerkstelligen,  dass  man  die  Grenzwerte  des 
Leitvermogens  mit  (1-n),  der  Ueberfiihrungszahl  des  Rat- 
ions, multipliziert;  das  Produkt,  die  molekulare  Beweglich- 
keit  des  Silberions,  muss  konstant  sein. 


KINETIK  DER  GELOSTEN  KORPER    269 


TAB.  6 


XX108 

(l-») 

\.(l-7l)108 

XX  108 

(1-n) 

X.  (1-71)108 

AgN03 
AgC103 
AgC104 
Ag04SC2H5 

1242 
1172 
1208 
956 

0-477 
0-499 
0-486 
0-615 

592 

585 
587 
588 

Ag03SC10H7 
Ag03SC8H5 
AgOISC,H11 
Ag02C2H3 

958 
913 

842 
956 

0-614 
0-653 

0-707 
0-624 

588 
596 
595 
597 

Die  Beweglichkeit  des  Ag  ergiebt  sich  aus  den  verschiedenen 
Salzen  nahezu  gleich;  die  Schwankungen  um  den  Mittelwert, 
591X10"8,  bleiben  innerhalb  der  Grenzen,  welche  durch 
ungtinstige  Haufung  der  Beobachtungsfehler  gegeben  sind. 
Hierdurch  erhalten  die  neuen  Anschauungen  iiber  die  Elek- 
trolyse  eine  wiederholte  Bestatigung. 

Durch  obigen  Mittelwert,  welcher  fiir  25°  giiltig  ist,  diirfte 
die  Beweglichkeit  des  Silberions,  falls  der  den  Messungen  von 
Herrn  Kohlrausch  entnommene  Wert  fur  den  Grenzwert  des 
Leitvermogens  von  Silbernitrat  keinen  in  Betracht  kommen- 
den  Fehler  enthalt,  bis  auf  wenige  Tausendstel  sicher  gestellt 
sein.  Indem  wir  aus  den  bei  0°  am  salpetersauren  und  pseudo- 
kumolsulfonsauren  Silber  ausgefiihrten  Bestimmungen  [962] 

\> 

von  n  (Tab.  2)  und  dem  mittelst  v~  aus  Tab.  4  auf  0°  umge- 

A26 

rechneten  X  das  entsprechende  Produkt  bilden, 
1242X0.461X0.548=314 


842X0.727X0.517=  317 


Mittel  315.5, 


finden  wir  die  Beweglichkeit  des  Silberions  bei  0°  und  konnen 
so  durch  Subtraktion  dieser  Zahl  von  den  auf  0°  umgerech- 
neten  Leitvermogen  der  ubrigen  untersuchten  Salze  auch 
zu  den  Geschwindigkeiten  der  ubrigen  Jonen  bei  0°  gelangen. 
Uebrigens  liegt  in  der  Uebereinstimmung  der  beiden  obigen 
Werte  ein  neuer  Beweis  fiir  die  Richtigkeit  des  zu  priifenden 
Gesetzes. 


270 


MORRIS  LOEB 


In  der  f olgenden  Tabelle  sind  unter  I  die  Jonengeschwind- 
igkeiten  bei  25°,  unter  II  diese  Grossen  bei  0°,  unter  III  die 
Temperaturkoeffizienten  a  zwischen  25°  und  0°  nach  der 
Formel  v=v^  (l+a(J— 25))  berechnet. 


TAB.  7 


08SC8Hn 

03SC6H5 

02C2H3 

04S02H5 

03SC10H7 

C103 

Ag 

C104 

N03 

I    248 

318 

361 

368 

369 

587 

591 

621 

640 

XlO-a 

II    118 

156 

183 

— 

180 

322 

316 

347 

364 

« 

III    210 

203 

197 

*~ 

198 

181 

186 

177 

175 

XIO-* 

Wie  nahe  die  unter  I  aufgefiihrten  Beweglichkeiten  sich 
den  beobachteten  Zahlen  anschliessen,  lehrt  Tab.  8. 


TAB.  8 


X  beob. 

Xber. 

Diff. 

n  beob. 

n  ber. 

Diff. 

AgO,SC,H11 

842 

839 

-  3 

0-293 

0-295 

+0-02 

Ag03SC6H5 

913 

909 

-4 

0-347 

0-350 

+0-03 

Ag02C2H3 
Ag04SC2H5 

956 
956 

952 
959 

-4 
+  3 

0  376 
0-385 

0-379 
0-384 

+0-03 

-o-oi 

Ag03SC10H7 
AgOlO, 

958 
1172 

960 

1178 

+  2 
+  6 

0-386 
0-501 

0-384 
0  499 

-0-02 
-0-02 

AgC104 

1208 

1212 

+  4 

0-514 

0-512 

-0-02 

AgNOg 

1242 

1240 

-2 

0-523 

0-524 

+0-01 

Ein  Blick  auf  Tabelle  7,  in  welcher  die  Beweglichkeiten 
nach  ihrer  Grosse  geordnet  sind,  lasst  eine  auffallende  Be- 
ziehung  des  Temperaturkoeffizienten  hierzu  erkennen.  Mit 
zunehmender  Beweglichkeit  nimmt  der  Tem- 
peraturkoeffizient  ab.  Es  sei  noch  hinzugefiigt,  dass 
die  entsprechenden  Temperaturkoeffizienten  der  einwertigen 
Jonen  OH  und  H,1  welche  durch  besonders  grosse  Beweg- 
lichkeit ausgezeichnet  sind,  sich  an  obige  Reihenfolge  eben- 
falls  anschliessen. 

1  Nernst,  Zeitschr.  2,  626. 


KINETIK  DER  GELOSTEN  KORPER    271 

[963] 


OH 

H 

I 

187 

350 

xio-8 

III 

159 

137 

Xl(T4 

Eine  Folge  dieser  Gesetzmassigkeit  ware,  dass  mit  steigen- 
der  Temperatur  die  Ueberfiihrungszahlen  dem  Werte  0*5 
zustreben,  die  Leitvermogen  \m  der  verschiedenen  Salze 
sich  einander  nahern.1 

Suchen  wir  auch  aus  den  beiden  untersuchten  Salzen 
zweibasischer  Sauren  die  Beweglichkeit  des  Silbers  zu  be- 
rechnen,  indem  wir  aus  Tabelle  4,  Ao,  extrapolieren,  so  er- 
geben  sich 

ausAg2S2O6:    1540X0.394=0.607, 
"   Ag2SiFl6:  1120X0.534=0.598, 

somit  etwas  grossere  Zahlen,  als  bei  den  einwertigen  Salzen. 
Um  nicht  mit  unseren  Anschauungen,  wonach  dem  Silberion, 
gleichviel  ob  es  durch  Dissoziation  aus  einem  ein-  oder 
mehrbasischen  Salze  entstanden  ist,  dieselbe  Beweglichkeit 
zuzuschreiben  ist,  in  Widerspruch  zu  geraten,  miissen  wir 
annehmen,  dass  die  von  uns  bei  dem  Gehalte  0.025  resp. 
0.028  gemessene  Ueberfiihrungszahl  sich  noch  mit  abneh- 
mender  Konzentration  andern  muss.  Leider  war  es  in  dieser 
Arbeit,  welche  infolge  der  Abreise  von  Einem  von  uns  zum 
Abschluss  gebracht  werden  musste,  nicht  moglich,  diese 
Forderung  der  Theorie  zu  priifen;  doch  sei  noch  kurz  darauf 
hingewiesen,  dass  nach  der  Dissociationshypothese  eine  Aen- 
derung  von  n  mit  dem  Gehalte  bei  so  grossen  Verdiinnungen, 
bei  denen  die  binaren  Elektrolyte  bereits  eine  konstante 
Ueberfiihrungszahl  aufweisen,  fur  die  Verbindungen  zwei- 
basischer Sauren  wahrscheinlich  ist.  Die  Dissociationspro- 
dukte  von  Ag2S2O6  z.  B.  sind  Ag,  AgS2O6  und  S206;  es  geht 

1  Vergl.  auch  Arrhenius,  loc.  cit.  45  (1884). 


272  MORRIS  LOEB 

daraus  hervor,  dass  selbst  bei  obigen  Verdunnungen  neben 
den  Jonen  4-Ag,  +Ag,  -S2O6,  auf  welche  wir  soeben  Kohl- 
rauschs  Gesetz  anzuwenden  gesucht  haben,  noch  solche  in 
nicht  unbetrachtlicher  Zahl  von  der  Beschaffenheit  +Ag, 
-AgS2O6  existieren;  mil  einer  fortschreitenden  Dissoziation 
dieser  in  jene  ist  dann  natiirlich  eine  Aenderung  der  Ueber- 
fiihrungszahl  verkniipft.  Es  sind  hier  somit  ahnliche  Erwa- 
gungen  anzustellen  wie  die,  durch  welche  Herr  Hittorf  bereits 
vor  29  Jahren1  gelegentlich  der  Beobachtung  anomaler 
Ueberfiihrungszahlen  bei  Jodkadmium  die  Schwierigkeiten, 
welche  hierdurch  seiner  Theorie  erwuchsen,  so  gliicklich 
beseitigt  hat. 

1  Hittorf,  Pogg.  Annalen,  106,  546  (1859). 


[106]    THE   RATES  OF  TRANSFERENCE    AND 

THE    CONDUCTING     POWER     OF     CERTAIN 

SILVER    SALTS1 

1.  INTRODUCTION 

WHENEVER  a  current  of  electricity  is  passed  through  a 
conductor  of  the  second  class,  under  such  conditions  that  the 
composition  of  the  solution  is  not  changed,  as  when  a  current 
passes  between  electrodes  of  the  same  metal  in  a  solution  of 
a  salt  of  that  metal,  curious  changes  of  concentration  appear. 
This  was  noticed  by  many  scientists,  but  it  was  reserved  for 
Hittorf  to  investigate  these  changes  quantitatively  and  to 
advance  a  plausible  and  exhaustive  hypothesis  of  their  causes. 
His  work  constitutes  one  of  the  classics  in  physics;  but  as  it 
is  not,  perhaps,  so  generally  known  to  chemists,  a  short  ex- 
planation of  his  hypothesis  may  be  a  not  inappropriate  in- 
troduction to  our  paper.  Taking  the  example  already  cited, 
it  is,  of  course,  a  familiar  principle,  that  in  a  given  interval 
the  same  amount  of  metal  is  dissolved  from  the  positive  elec- 
trode as  is  deposited  upon  the  negative  electrode.  If  we  were 
to  assume  that  the  ions  of  the  electrolyte  were  incapable  of 
moving  independently  of  each  other,  the  changes  in  concen- 
tration at  the  two  electrodes  could  only  be  counterbalanced 
by  the  slow  process  of  diffusion,  and  we  should  find  a  deficit 
in  the  liquid  around  the  negative  electrode  corresponding 
to  the  amount  of  metal  deposited  upon  the  latter,  while  all 
the  metal  yielded  up  by  the  positive  electrode  would  be  found 

1  In  collaboration  with  Walther  Nernst.  Reprinted  from  American  Chemical 
Journal,  11,  106  (1889).  This  paper  is  an  abbreviated  translation  of  the  fore- 
going monograph,  made  by  Dr.  Loeb.  [EDITOR.]  , 


274  MORRIS  LOEB 

in  its  immediate  surroundings.  This  is,  of  course,  an  unten- 
able assumption.  Supposing,  on  the  other  hand,  that  only  the 
negative  ions  were  immovable,  while  the  positive  ones  could 
travel  across  the  liquid  as  fast  as  required  to  supply  the  places 
of  those  disappearing  upon  the  negative  electrode :  the  liquid 
would  be  homogeneous  at  all  moments,  and  there  would  be 
no  concentration  nor  dilution  around  the  electrodes.  We  can- 
not, however,  assume  that  the  negative  ions  are  immovable, 
everything  showing  that  they  move  toward  the  cathode 
just  as  well  as  the  positive  ones  do  toward  the  anode.  If  both 
move  [107]  with  equal  rapidity,  as  was  tacitly  assumed  be- 
fore Hittorf ,  a  little  reflection  will  show  that  the  liquid  about 
the  cathode  will  lose  just  half  as  much  metal  as  is  deposited 
upon  the  electrode,  while  half  the  metal  given  up  by  the 
anode  to  the  surrounding  liquid  will  have  been  transferred 
toward  the  cathode.  Hittorf 's  laborious  analyses  proved  that 
none  of  these  three  possibilities  was  fulfilled.  The  relation 
between  the  changes  in  concentration  and  the  amount  of 
metal  transferred  from  one  electrode  to  the  other  proved 
conclusively  that  the  two  classes  of  ions  did  not  move  with 
equal  rapidity;  and  he  showed  how  this  ratio  provided  a 
measurement  of  the  share  of  each  class  in  the  total  movement. 
For  any  salt,  [the  reciprocal  of]  the  ratio  of  the  weight  of  the 
metal  deposited  to  the  amount  of  metal  lost  by  the  fluid 
around  the  cathode  (or  its  equivalent,  the  amount  gained 
by  that  around  the  anode)  represents  the  share  of  the  nega- 
tive ion,  the  anion,  in  the  total  movement. 

Hittorf  has  had  few  followers  in  these  investigations,1  as 
the  difficulties  of  experiment  were  discouraging.  Analytical 
accuracy  demanded  the  use  of  concentrated  solutions,  or  of 

1  The  following  list  includes  all  the  literature;  Hittorf,  Pogg.  Annalen,  89,  177, 
98,  1,  103,  1,  106,  337;  G.  Wiedemann,  Ibid.  99,  177;  Weiske,  Ibid.  103,  466; 
Kuschel,  Wied.  Annalen,  13,  289;  Kirmis,  Ibid.  48,  503;  Lenz,  M6m.Ac.  St.  Ptters- 
bourg,  30, 1882. 


KINETICS  OF  CERTAIN  SILVER  SALTS    275 

bulky  and  cumbrous  apparatus,  while  it  was  especially  de- 
sirable to  study  dilute  solutions,  and  to  use  apparatus  which 
was  not  subject  to  such  disturbances  as  variations  of  tempera- 
ture, osmose,  and  the  jars  unavoidable  during  mechanical 
handling  produce.  Considerations  which  will  be  explained 
later  led  us  to  attempt  the  acquisition  of  fresh  material,  es- 
pecially with  reference  to  highly  dilute  solutions.  We  found 
that  we  could  do  this  by  studying  certain  silver  salts,  mainly 
organic;  and  we  were  led  to  this  choice  firstly  because  silver 
is  the  only  monovalent  metal  which  furnishes  a  satisfactory 
electrode  —  a  matter  of  some  moment  for  our  subsequent 
work;  secondly,  because  its  salts  are  readily  obtained  in  the 
needful  state  of  purity;  finally,  because  Volhard's  beautiful 
method  of  titration  l  enabled  us  to  perform  the  necessary 
analyses  with  great  ease  and  extreme  nicety.  We  also 
availed  ourselves  of  the  opportunity  for  studying  the  effects 
of  temperature  and  concentration  upon  the  velocity  of  the 
ions  of  these  salts,  because  one  of  us  2  has  recently  shown  how 
important  a  part  is  played  by  these  factors  in  the  kinetics  of 
solutions. 

[108]    2.  APPARATUS  FOR  THE  DETERMINATION  OF  THE 
RATE  OF  TRANSFERENCE 

In  this  apparatus  we  wished  to  avoid  the  use  of  membra- 
nous diaphragms,  and  to  minimize  the  internal  resistance, 
necessarily  large  by  reason  of  our  very  dilute  solutions,  so 
as  to  keep  the  necessary  duration  of  an  experiment  within 
reasonable  limits.  After  various  failures  we  finally  hit  upon 
a  form  whose  simplicity  is  likely  to  recommend  it  in  similar 
cases.  As  shown  in  the  accompanying  drawing,  it  is  seen  to 
resemble  the  Gay-Lussac  burette,  but  with  the  addition  of 
a  short  side-tube  of  the  same  bore  as  the  main  tube.  This  side- 

1  Volhard,  Annalen,  190,  1.  2  Nernst,  Zeitschr.  2,  613. 


276 


MORRIS  LOEB 


tube  ends  in  a  bulb,  and  upon  this  is  set  a  narrower  vertical 
tube,  through  which  the  negative  electrode  —  a  cylindrical 

roll  of  silver  foil  fastened  to  a  sil- 
ver wire  —  can  be  let  down  into 
the  bulb.  This  works  as  a  sort 
of  pocket,  by  which  masses  of  the 
spongy  precipitated  silver  that 
may  become  detached  from  the 
electrode  are  prevented  from  stir- 
ring up  the  body  of  the  solution. 
The  anode  consists  of  a  silver  wire 
rolled  into  a  spiral  at  the  lower 
end.  It  is  introduced  through  A, 
and  reaches  to  the  bottom  of  the 
main  tube.  In  order  that  the  cur- 
rent may  enter  the  liquid  only 
at  the  spiral,  the  straight  part  of 
the  wire  is  covered  with  a  capillary  of  very  thin  glass,  which 
can  be  closed  around  the  wire  by  fusion,  in  spite  of  the 
difference  in  their  coefficients  of  expansion.  The  openings 
A  and  B  are  closed  with  corks  that  are  traversed  by  short 
glass  tubes.  Of  these,  the  tube  at  A  allows  free  passage  to  the 
wire  of  the  electrode.  The  wall  of  the  tube  at  B  is  pierced  by 
a  platinum  wire,  which  serves  to  suspend  the  cathode  and  to 
connect  it  with  the  conductor  of  the  battery.  Thus  A  can  be 
closed  by  the  compression  of  a  bit  of  rubber  tubing  drawn 
over  the  wire  and  glass  tube,  or  air  can  be  sucked  or  blown 
through  a  rubber  tube  connected  with  B,  without  disturb- 
ing the  electrodes. 

[109]  In  experimenting,  such  an  apparatus  would  first  be 
weighed  with  its  electrodes  and  stoppers,  but  without  the 
rubber  tubing.  The  latter  was  hereupon  put  in  position,  A 
was  closed  with  a  pinch-cock  as  just  indicated,  and  air  was 


KINETICS  OF  CERTAIN  SILVER  SALTS    277 

drawn  out  at  B  while  the  nozzle  C  was  dipping  under  the  sur- 
face of  the  solution  to  be  used.  By  this  process,  the  main-  and 
side-tubes  were  filled  up  to  the  level  of  the  top  of  the  latter; 
the  sizes  of  apparatus  we  employed  contained  40  and  60  cc. 
respectively.  The  nozzle  was  now  likewise  closed  with  a  rubber 
cap,  and  the  whole  apparatus  suspended  in  one  of  Profes- 
sor Ostwald's  thermostatic  water-baths,1  in  such  a  fashion 
that  the  nozzle  protruded  over  the  rim,  while  the  liquid 
was  entirely  within  the  water-bath.  After  it  had  acquired 
the  temperature  of  the  bath,  the  circuit  was  closed.  As  soon 
as  the  electrolysis  was  concluded,  the  nozzle  was  opened  and 
suitable  portions  of  the  liquid  were  filled  into  tared  vessels, 
by  blowing  steadily  through  B.  These  portions  were  weighed 
and  analyzed.  The  portion  remaining  in  the  apparatus  was 
estimated  by  the  latter's  gain  in  weight,  and  likewise  analyzed. 
Provided  there  has  been  no  mixing  through  diffusion  and  con- 
vection during  the  electrolysis,  the  first  portion  taken  from 
the  apparatus,  if  the  liquid  is  properly  divided,  will  consist 
of  the  stratum  around  the  anode,  which  has  become  more 
concentrated,  and  of  a  sufficient  quantity  of  the  unaltered 
middle  layers  to  insure  a  rinsing  of  the  adhering  parts  of  the 
lowest  stratum.  The  succeeding  portions,  being  composed 
wholly  of  the  middle  layers,  must  show  an  unaltered  compo- 
sition, while  what  is  left  in  the  apparatus  includes  the  diluter 
strata  about  the  cathode.  To  prove  the  reliability  of  our  ex- 
periment, we  must  find  in  the  first  place  that  the  middle 
layers  had  remained  unchanged,  and  secondly,  that  the 
gain  of  the  lowest  layer  exactly  counterbalanced  the  loss  of 
the  highest,  for  the  mean  composition  of  the  whole  liquid 
undergoes  no  change.  After  finding  that  the  first  condition 
was  invariably  fulfilled,  we  saved  time  by  giving  up  the  sep- 
arate examination  of  the  middle  layers,  and  divided  the  whole 

1  As  described  recently  by  Professor  Ostwald,  Zeitschr.  2,  565. 


278  MORRIS  LOEB 

liquid  into  two  nearly  equal  portions.  It  frequently  happened 
that,  during  the  electrolysis,  the  electrolyzed  silver  would 
grow  out  from  the  bulb  along  the  wall  of  the  horizontal 
tube.  In  such  cases  the  circuit  was  broken  before  the 
silver  had  reached  the  main  tube;  otherwise,  [110]  we  dis- 
connected whenever  we  estimated  that  a  sufficient  change 
of  concentration  had  taken  place  to  give  the  most  reliable 
results. 

The  analyses  were  performed,  as  already  intimated,  by 
titration  with  a  solution  of  ammonic  sulphocyanate,  the 
standard  of  which  (about  j^  normal)  was  ascertained  by  fre- 
quent comparison  with  an  argentic  nitrate  solution  of  known 
strength,  occasional  gravimetric  determinations  of  which 
gave  absolutely  constant  results.  We  claim  for  the  titrations 
an  error  well  within  ^  cc.  (=  0.038  milligrams  Ag),  each 
end-reaction  being  observed  twice,  as  1  cc.  of  a  ^  normal 
solution  of  argentic  nitrate  was  added  from  a  pipette,  after 
the  first  appearance  of  the  characteristic  tint,  and  the  titra- 
tion repeated. 

The  ratio  we  are  seeking  to  determine  requires,  besides  the 
data  of  the  change  in  concentration,  the  weight  of  the  silver 
which  has  been  actually  deposited  upon  the  cathode,  in  the 
same  interval  of  time.  This  would  most  naturally  be  deter- 
mined by  a  silver  voltameter  placed  in  the  same  circuit  with 
the  apparatus.  But  as  the  examination  of  dilute  solutions 
often  necessitated  the  deposit  of  less  than  20  milligrams  in 
all,  and  the  silver  is  deposited  in  such  a  form  upon  the  vol- 
tameter that  it  is  difficult  to  weigh  it  without  a  slight  loss,  we 
found  it  to  be  more  advantageous  to  determine  the  quantity 
of  electricity  which  traversed  the  apparatus  by  galvanometric 
measurement.  A  resistance-box  was  introduced  into  the  cir- 
cuit for  this  purpose  (see  figure),  to  the  extremities  of  which 
a  second  circuit  was  connected,  containing  a  Clark's  cell  and 


KINETICS  OF  CERTAIN  SILVER   SALTS    279 

a  galvanometer  with  direct  reading.  The  Clark's  cell  being 
introduced  in  the  proper  direction,  it  is  well  known  that  a 
suitable  resistance  R  may  be  introduced  by  means  of  the  box, 
which  will  put  the  galvanometer  at  rest  at  the  0  point;  when 
this  is  effected,  we  have  for  the  electrical  intensity  of  the  main 

E 

current  i  =  —>E  denoting  the  electromotive  force  of  the  stand- 
R 

ard  Clark's  cell.  As  the  intensity  of  the  current  changed  but 
little  and  very  gradually  during  the  four  or  five  hours  which 
were  usually  occupied  by  an  electrolysis,  we  were  satisfied 
with  making  this  measurement,  which  required  but  a  few 
seconds'  attention,  every  ten  minutes.  The  total  amount 
of  electricity  could  then  be  integrated  with  sufficient  cer- 
tainty. 

Special  experiments  showed  that,  when  resistance-box  and 
[111]  Clark's  cell  were  at  a  temperature  of  18°  C.,  the  quan- 
tity /  of  precipitated  silver  could  be  found  by  the  formula, 

/  =^92.69, 

where  T  represents  the  duration  of  the  electrolysis  in  minutes, 
while  r  denotes  the  resistance  which  would  have  been  neces- 
sary to  keep  the  galvanometer  at  0,  provided  that  amount 
of  electricity  which  actually  passed  through  the  apparatus 
had  done  so  in  a  current  which  remained  constant  throughout 
this  interval.  Whenever  the  resistance-box  and  the  cell  were 
at  any  other  temperature,  t,  the  above  expression  must  be 
multiplied  with  the  factor  1-0.0012  (Z-18).  This  coefficient 
of  temperature,  0.0012,  is  derived  from  that  of  the  cell, 
-0.0008,  and  that  of  the  box,  +0.0004. 

Our  battery  consisted  of  38  Leclanche  cells,  with  a  com- 
bined electromotive  force  of  about  40  volts  and  an  internal 
resistance  of  about  120  ohms.  It  furnished  a  current  which 


280  MORRIS  LOEB 

remained  practically  constant  for  many  hours,  when  enclosed 
in  a  circuit  of  5000-10,000  ohms  resistance.  It  also  had  the 
advantage  of  being  always  ready  for  use. 

3.  PREPARATION  OF  THE  SILVER  SOLUTIONS 

The  solutions  of  argentic  nitrate  were  prepared  from  the 
crystallized  salt.  Those  of  the  chlorate,  perchlorate,  ethyl- 
sulphonate,  naphthalene-sulphonate,  benzene-sulphonate, 
pseudo-cumene-sulphonate  and  acetate,  were  made  by  neu- 
tralizing known  amounts  of  these  acids  with  moist  argentic 
oxide,  passing  the  solution  through  an  asbestos  filter,  and 
diluting  to  a  suitable  volume.  Argentic  dithionate  (Ag2S2O6) 
was  obtained  by  the  reaction  of  exactly  equivalent  quantities 
of  baric  dithionate  and  argentic  sulphate.  To  make  ar- 
gentic fluosilicate,  a  solution  of  hydrofluosilicic  acid  was 
saturated  with  argentic  oxide;  dilute  baric  hydrate  solution 
was  then  added  cautiously,  until  the  brown  color  of  argentic 
oxide  commenced  to  appear  in  the  precipitate  of  baric  fluo- 
silicate. The  neutral  solution  was  then  filtered  and  diluted. 

4.  DESCRIPTION  OF  A  DETERMINATION  IN  DETAIL 

The  description  of  this  determination,  made  with  a  solution 
of  argentic  nitrate  which  was  about  ^  normal,  will  best 
illustrate  our  method  of  experiment  and  calculation.  The 
electrolysis  was  [112]  conducted  at  a  temperature  of  26°,  and 
the  solution  thereupon  divided  into  four  portions,  which  are 
numbered  in  the  following  table  in  the  order  in  which  they 
were  taken  out;  consequently,  No.  1  represents  the  lowest 
stratum  in  the  apparatus.  Column  I  contains  the  weights  of 
these  portions;  II,  the  amount  of  silver  found  in  each;  III, 
the  amount  each  portion  would  have  contained  if  no  change 
had  occurred,  estimated  from  the  fact  that  1  gram  of  the 
solution  originally  contained  1.139  milligram  of  silver. 


KINETICS  OF  CERTAIN  SILVER  SALTS    281 

TABLE  I 


Portion 
1 
2 
3 
4 

I 

20-09  grams 
5-27 
5-33 
27-12 

II 

39-66millig. 
5-96 
6  04 
14-14 

III 

22-88millig. 
6-00 
6-07 
30-89 

Diff. 

+16-78millig. 
-  0-04 
-  0-03 
-16-75 

57-81  65-80 

It  will  be  seen  that  the  strength  of  two  middle  portions  has 
remained  constant,  within  the  errors  of  determination;  we 
also  find  a  close  agreement  in  the  second  test,  which  demands 
that  the  mean  concentration  shall  remain  unchanged;  the 
value  65.80/57.81  =  1.138,  scarcely  different  from  the  original 
strength  1.139. 

The  measurement  of  the  electrical  current  as  described 
above  informed  us  that  a  quantity  of  electricity  equivalent 
to  the  precipitation  of  32.10  mg.  of  silver  had  passed  through 
the  apparatus;  while  a  silver- voltameter,  placed  in  the  circuit 
for  our  better  assurance,  contained  32.2  mg.;  the  former  value 
was  accepted  as  the  more  trustworthy. 

Following  Hittorf,1  we  based  these  calculations  upon  our 
data:  The  solution  at  the  anode  (1)  received  from  the  latter 
32.1  mg.  Ag,  and  the  uppermost  layer  (4)  gave  up  the  same 
amount  to  the  cathode.  Owing  to  the  changes  in  concentra- 
tion, the  values  in  the  above  table  are  not  absolutely  correct, 
since  1  gram  of  solution  does  not  always  contain  the  same 
weight  of  water,  as  had  been  provisionally  assumed.  But  the 
necessary  correction  is  small  and  readily  made.  Let  v  be 
the  ratio  of  the  molecular  weights  of  silver  and  the  salt  in 
question;  in  this  special  case  v  =  ^  =  1.57.  Let  a  represent 
the  amount  of  silver  contained  in  1  gram  of  [113]  unaltered 
solution,  being  consequently  dissolved  in  (I—av)  grams  of 
water.  If,  after  electrolysis,  q  grams  of  the  solution  about 
one  electrode  are  found  to  contain  b  grams  of  silver,  the 

1  Hittorf,  Pogg.  Annalen,  98,  19. 


282  MORRIS  LOEB 

a(q-bv)        b-aq 

gain  or  loss  will  be  represented  by ±6 —  =± . 

l-av          I-av 

As  b-aq  is  the  value  given  in  the  column  of  differences,  the 

factor  represents  the  necessary  correction.     Conse- 

1—  av 

quently,  after  completing  the  deficit  of  portion  4  by  the 
addition  of  the  small  deficits  in  2  and  3,  we  have  for  the 
rate  of  transference  of  the  negative  ion, 

16.78  ,  16.82 

1.0017  and  -     -1.0017,  or  a  mean  value  of  0.524. 

32.10  32.10 

As  already  stated,  the  determination  was  usually  simplified 
by  dividing  the  liquid  into  two  portions  instead  of  four. 

In  this  experiment  there  was  a  second  apparatus  placed  in 
series  in  the  circuit;  hence  the  mean  intensity  of  the  current 
was  only  0.0012  ampere,  and  the  electrolysis  lasted  seven 
hours.  We  frequently  saved  time  and  used  our  battery  to 
better  advantage  by  performing  two  simultaneous  elec- 
trolyses in  parallel  circuits,  each  of  which  must,  of  course, 
contain  its  own  resistance-box;  by  means  of  a  properly 
constructed  switch,  we  could  apply  the  measuring  circuit  to 
either  box  at  will,  thus  securing  the  measurement  of  both 
electrolyses  with  the  same  galvanometer  and  element.  We 
may  also  state  here  that  the  last  was  frequently  compared 
with  another  cell  of  the  same  construction  and  was  always 
found  to  be  exactly  equivalent  to  it  in  electro-motive  force, 
a  proof  that  it  did  not  vary  during  the  course  of  our 
experiments. 

5.  RATES  OF  TRANSFERENCE  OF  THE  NEGATIVE  ION 

Hereafter  t  implies  the  temperature  during  electrolysis; 
m  the  molecular  concentration  (gram-molecules  per  liter); 
/i  the  milligrams  of  silver  precipitated  on  the  cathode  accord- 


KINETICS  OF  CERTAIN  SILVER  SALTS    283 

ing  to  galvanometric  measurement  ;/2  the  same  value  accord- 
ing to  the  voltameter  whenever  it  was  used;  n  the  rate  of 
transference. 

Argentic  Nitrate 

1)  £  =  20°           m  =  0-1043           .ft  =  83-5           /2  =  83'6  7i  =  0'528 

2)  £  =  26°            m  =  0-0521           /t  =  76'7  w  =  0'524 

3)  £  =  26°            ra  =  0-0250           /1==48'0  71  =  0.5223 
4)*=    0°           m  =  0-0250           /1==48-0  7i  =  0'5383 
5)  £  =  26°           771  =  0-0105           ^  =  32-10         /2  =  32'2  ft,  =  0'524 
6)2  =  26°            ra  =  0'0105           ^  =  32-10         /2  =  32'2  7i  =  0'524 

[114]  In  3)  and  4)  and  in  5)  and  6)  both  pieces  of  apparatus  were  in  the  same  cir- 
cuit. 

Argentic  Chlorate 

1)^  =  24-8°         771  =  0-0245         /.=  39-88          /2=39'5  7i  =  0'503 

2)  £  =  24-8°          w  =  0-0245         ^  =  51-72  7i  =  0'499 

Argentic  Perchlorate 

1)  £  =  24-8°          m  =  0-0247         .ft  =  39- 88           /2  =  39"5  7i  =  0'515 

2)^  =  24-8°          m  =  0-0247         ^  =  51-72  7i  =  0'512 

In  studying  these  two  solutions,  1)  and  1)  and  2)  and  2)  were  in  the  same  cir- 
cuits. 

Argentic  Ethyl-sulphonate 

1)^  =  24-8°          m  =  0-0243         ,ft  =  58-30  7i  =  0'385 

2)^  =  24-8°          rri  =  0-0243         ^  =  48-47           /2=48'34  n  =  0'389 

3)  £  =  25°             m  =  0-00606       ^  =  18-10  7i  =  0'384 

Argentic  Benzene-sulphonate 

2)^  =  24-7°          m=0-0250          /J  =  17-85  7i  =  0'351 
2)  of  the  former  and  1)  of  the  latter  solution  were  electrolyzed  in  series. 

Argentic  Pseudocumene-sulphonate 

1)^  =  24-2°          771  =  00235          /,=61'62  n  =  0'293 

2)^  =  29-2°           m  =  0-02216        /,=38'24  7i  =  0'2947 

3)^  =  0°                771  =  0-02216        .ft  =  38-24  n  =  0'2732 

4)^  =  0°                771  =  0-02216        .ft  =  42'79  7i  =  0'2731 

2)  and  3)  were  electrolyzed  in  series. 

Argentic  Naphthalene-sulphonate 

1)  £  =  29-2°          771  =  0-01292        /t  =  33'95  n-0'390 

2)^  =  25-0°          m  =  0-0250          /1  =  39'75         /2  =  39'5  n  =  0'386 


284  MORRIS  LOEB 

Argentic  Acetate 

In  examining  this  salt,  we  were  surprised  to  find  that  the 
middle  layers  of  the  solution  did  not  remain  unchanged,  and 
that  the  mean  concentration  after  electrolysis  did  not  agree 
with  the  [115]  original  standard.  This  irregularity  is  probably 
due  to  the  slight  solubility  of  the  salt,  since  it  can  easily 
happen  that  the  solution  about  the  anode  becoming  over-con- 
centrated, some  of  the  salt  crystallizes  out  and  vitiates  the 
result.  In  fact,  we  did  succeed  in  obtaining  reliable  values 
when  we  had  recourse  to  a  highly  dilute  solution. 

1)  *  =  25°  77i  =  0-00972  /t  =  20-80  7i  =  0'375 

2)  *  =  24°  m  =  0-00972  /1  =  23'99  tt  =  0'377 

Argentic  Dithionate 

1)  f  =  24-8°  771  =  0-0246  ^  =  33-40  n  =  0'604 

2)  *  =  29'2°  w  =  0-0246  /x  =  46-70  n  =  0'604 
8)  t=   0°                       m  =  0-0246                   /!  =  46-70                   7i  =  0'605 

4)  £  =  24  2°  m  =  0-0246  /1  =  48-85  ft  =  0'606 

5)  t=   0°  771  =  0-0246  ^  =  45-80  n  =  0-603 

2)  and  3)  were  electrolyzed  in  series. 

Argentic  Fluosilicate 

1)  £  =  22 -2°  m  =  0-02815  ^  =  60-28  n  =  0'647 

2)  *  =  22-2  m  =  0-02815  ^  =  37-44  n  =  0'647 

In  Table  II  we  summarize  these  values  of  n,  with  the 
corresponding  temperatures  and  concentrations. 

TABLE  II 

Argentic  n  t  m 

Nitrate 0'523  25°  )       ft-1       O.ft1 

0-539  0°  ] 

Chlorate 0'505  25°  0-0245 

Perchlorate 0"514  25°  0  0247 

Ethyl-sulphonate    .     .     .     .     0'385  25°  0-0243-0-0061 

Naphthalene-sulphonate .     .0-390  30°  In- no™      A.AIQ 

0-386  25°  /°  Ux}5U 

Pseudocumene-sulphonate  .    0'293  25°  \o-09q 

0-273  0°  /°023 

Benzene-sulphonate    .     .     .     0'347  25°  0'025 

Acetate  0"376  25°  0-097 


Dithionate 0-604  25° 

0-604  0° 

Fluosilicate   .  .0'466  22°  0'0282 


0-604  Oo  }°0346 


KINETICS  OF  CERTAIN  SILVER  SALTS    285 

Argentic  nitrate  has  been  carefully  studied  by  Hittorf,1 
who  found  that  between  the  concentrations  0.3  and  0.024 
the  rate  of  transference  does  not  vary,  the  mean  value  being 
0.526  at  19°.  We  came  to  the  same  conclusions  for  variations 
of  concentration  [116]  from  0.1  to  0.01,  and  we  found  a  value 
which,  when  reduced  to  the  same  temperature,  very  nearly 
agreed  with  his,  0.527  at  19°.  The  acetate  result  given 
above  also  agrees  well  with  Hittorf  's  (0.373  where  2  =  15°  and 
m=  0.05). 

6.  CONDUCTING  POWER  OF  THE  SILVER  SALTS  AND  ITS  RELA- 
TION TO  THE  RATE  OF  TRANSFERENCE 

It  will  be  noted  that  the  rate  of  transference  is  a  value 
varying  with  the  compound,  since  it  merely  expresses  the 
share  of  the  one  ion  in  the  total  movement.  If  u  is  the  ac- 
tual velocity  of  the  positive  ion  and  v  that  of  the  anion, 

n=  -  ;  and  the  rate  of  the  positive  ion,  l-n=  --  .    Kohl- 

u+v  u+v 

rausch,2  as  is  well  known,  has  propounded  the  simple  hy- 
pothesis that  the  conducting  power  of  a  molecule  of  an 
electrolyte  is  represented  by  the  sum  of  the  velocities  of 

itsions> 


His  experiments,  however,  did  not  seem  to  give  the  re- 
quisite support  to  this  theory,  some  salts  giving  approximate 
results,  but  those  of  weak  bases  and  acids  giving  utterly  dis- 
cordant figures.  The  difficulty  is  removed  if  we  assume  that 
the  conduction  is  not  performed  by  all  the  molecules  of  the 
electrolyte,  but  only  by  those  whose  ions  are  actually  in 
independent  motion.  This  is  Arrhenius's  principle  of  conduc- 
tive activity.3  Kohlrausch's  values  for  molecular  conduc- 

1  Pogg.  Annalen,  89,  199. 

*  FT.  Kohlrausch,  Wied.  Annalen,  6,  1. 

1  S.  'Arrhenius,  Sur  la  conductibttiti,  etc.,  Stockholm,  1884. 


286  MORRIS  LOEB 

tivity  are  a  function  of  the  total  number  of  molecules  of  the 
electrolyte  between  the  electrodes;  according  to  Arrhenius, 
the  coefficient  of  activity,  i.e.,  the  proportion  of  molecules 
actually  engaged  in  conduction,  not  only  varies  for  different 
compounds,  but  also  increases  for  any  one  compound  with 
its  dilution,  and  approaches  unity  for  extreme  dilutions.  It  is 
only  in  this  limiting  case  that  Kohlrausch's  equation  becomes 
absolutely  true;  this  is  the  view  that  Kohlrausch  himself 
had  expressed  with  regard  to  his  law,  whose  accuracy,  he  said, 
could  only  be  tested  by  experiments  with  highly  dilute  solu- 
tions. Ostwald's  examination  of  the  conducting  power  of 
highly  attenuated  solutions  of  a  very  large  number  of  electro- 
lytes l  has  afforded  very  valuable  support  to  these  recent 
views. 

Since,  however,  the  quantities  u  and  v  are  so  closely  con- 
nected [117]  with  the  rate  of  transference  of  the  ions,  a  study 
of  the  latter  in  dilute  solutions  must  afford  powerful  means 
of  testing  the  truth  of  Kohlrausch's  law  with  Arrhenius's 
emendations.  This  was  the  chief  motive  of  our  work,  and  we 
must  now,  therefore,  proceed  to  compare  the  values  which  we 
have  given  in  section  5  with  the  conducting  power  of  the  same 
salts.  Accordingly,  the  necessary  measurements  of  conduc- 
tion were  made  by  one  of  us  (W.  N.),  by  Kohlrausch's  method 
which  with  various  valuable  modifications  has  been  described 
by  Professor  Ostwald.2  The  values  which  we  present  are 
scaled  upon  the  conducting  power  of  mercury  as  unity,  and 
the  calculations  are  based  upon  Kohlrausch's  determination 
of  the  molecular  conductivity  of  argentic  nitrate.3 

The  following  table  gives  the  conducting  power  of  the  dif- 

1  Zeitschr.  1,  61  and  97.  *  Ibid.  2,  563. 

3  As  Kohlrausch  worked  at  18°,  while  the  present  determinations  were  made  at 
25°,  the  coefficients  of  temperature  were  determined  by  special  experiments  for  va- 
rious dilutions  of  AgNOa.  For  the  details  of  these  results  we  must  refer  to  the  Ger- 
man version  of  our  paper. 


TABLE  III 

771 

X  X  108  at  25' 

AgN03 

AgC103 

AgC104 

0-025 

1126 

1045 

1109 

0-015 

1153 

1103 

1139 

0-007 

1188 

1123 

1160 

0  003 

1206 

1151 

1182 

0-0015 

1221 

1160 

1194 

0-0008 

1233 

1163 

1200 

KINETICS  OF  CERTAIN  SILVER  SALTS    287 

ferent  silver  salts.  The  molecular  concentration  (gram-mole- 
cules in  the  liter)  m,  was  calculated  from  the  percentage  com- 
position as  found  by  analysis,  and  the  specific  gravity  de- 
termined at  18°,  although  this  barely  differed  from  that  of 
water.  There  was  no  appreciable  contraction  when  additional 
water  was  added  for  dilution;  but  a  proper  correction  was 
made  for  the  conduction  by  the  water  itself,  which  was  found 
to  be  2.5  X10"10. 


Ag(C2H5S04)     Ag(C8H6SOs) 

846 

905  874 
930  897 
943  900 
949  906 

m  X  X  108  at  25° 

Ag(C8HnS03)     Ag(C10H7S03)     AgC2H3O3       £Ag2S2Ofl  £Ag2SiFl, 

0-025  734  ...  ...  1253  995 

0-015  762  882  ...  1343  1020 

0  007  791  893  897  1383  1054 

0-003  813  926  926  1442  1081 

0-0015  826  941  944  1474  1096 

0-0008  836  951  949  1505  1100 

[118]  Ostwald  has  found 1  that  the  sodium  salts  of  numerous 
monobasic  acids  have  almost  identically  progressing  coeffi- 
cients of  activity;  the  same  regularity  may  be  observed  in  the 
present  series.  The  ratios  of  the  conductivity  of  a  salt  in  va- 
rious states  of  dilution  agree,  for  the  silver  salts  of  the  mono- 
basic acids,  within  limits  that  scarcely  transcend  the  probable 
errors  of  observation.  We  shall  utilize  this  fact  in  finding 
the  limit  of  the  conductivity  for  extreme  dilution;  for,  at 
the  concentration  0.0008,  the  dissociation  of  the  molecules 
is  not  yet  complete,  although  very  nearly  so.  If  we  re- 
member that,  according  to  Kohlrausch's  measurements,  when 

1  Ostwald,  Zeitschr.  2,  847. 


288  MORRIS  LOEB 

m  =  0.0008,  ^  of  the  molecules  of  argentic  nitrate  are  disso- 
ciated, we  can  fairly  assume  that  the  limiting  values  of  X  for 
the  other  silver  salts  may  be  obtained  by  raising  by  0.75  per 
cent  the  values  found  for  m=  0.0008. 

Table  IV  summarizes  the  measurements  made  to  deter- 
mine the  effect  of  temperature  upon  conducting  power;  in 
these  the  platinum  electrodes  usually  employed  were  replaced 
by  silver  ones,  which  gave  very  sharp  readings.  The  mea- 
sured conductivities  at  0°,  18°,  and  28°  are  denoted  by  XQ,  X18 
and  X28  respectively;  to  obtain  the  coefficient  of  temperature 

Y^  must  be  diminished  by  1  and  divided  by  10;  ^-  was 

A18  A25 

calculated  from  such  an  interpolated  value  of  X25- 

TABLE  IV 


AgNOs     .......     0-1  0-638  1-213  0-555 

0-02  0-638  1-217  0'554 

0-005  0-632  1-222  0'548 

AgClOg     .......     0-005  0-626  1-222  0-542 

'AgClO4     .......     0-005  0-632  1*224  0-547 

AgCIOH7SO3  ......     0-005  0-615  1'242  0-526 

AgC,H5SO3  ......     0-005  0-607  1-241  0'519 

AgC2H302     ......     0-005  0-611  1-237  0-524 

AgC9HuSO3  ......     0-025  0-609  1-242  0'521 

0-006  0-606  1-246  0'517 

£Ag2S2Oe  .......     0-025  0-631  1-222  0'547 

0-006  0-631  1-226  0'544 


[119]     7.  TEST  OF  THE  LAW  OF  KOHLRAUSCH  FOR 
EXTREME  DILUTIONS 

For  this  purpose  we  need,  besides  the  limiting  values  for 
conduction,  which  we  have  just  shown  to  be  attainable,  the 
limiting  values  for  the  rate  of  transference,  likewise  for  ex- 
treme dilution. 

At  the  close  of  section  5  we  noted  that  Hittorf  found  the 
value  of  n  to  be  independent  of  the  state  of  dilution  where 


KINETICS  OF  CERTAIN  SILVER  SALTS    289 

m  <C  0.3  in  the  case  of  AgNO3,  and  that  we  confirmed  his 
result  by  our  own  experiments  on  this  and  other  salts. 
Consequently  the  values  found  for  this  rate,  whenever 
m  =  0.025—0.01,  can  be  assumed  to  hold  good  for  infinite 
dilutions.  The  reason  becomes  apparent  when,  considering 
the  inactive  molecules  as  stationary,  we  remember  that  a 
molecular  concentration  0.01  means  a  proportion  of  one  sil- 
ver ion  to  5550  molecules  of  H2O.  The  resistance  which 
such  an  ion  would  encounter  cannot  differ  from  that  of  pure 
water. 

The  testing  of  Kohlrausch's  law  can  now  be  readily  ac- 
complished by  multiplying  the  limiting  value  of  conductivity 
into  (1—  ft),  the  rate  of  transference  of  the  positive  ion;  the 
product,  which  represents  the  molecular  velocity  of  the  silver 
ion,  must  remain  constant  for  all  the  monobasic  salts. 

TABLE  V 
XX108  (1-rc)  X(l-n)108 

AgNO3 1242  0-477  592 

AgCIO, 1172  0-499  585 

AgC104 1208  0-486  587 

AgC2H5SO4 956  0-615  588 

AgC10H7SO3 958  0-614  588 

AgC6H5SO3 913  0-653  596 

AgC9HuS03 842  0.707  595 

AgC2H3O2 956  0-624  597 

The  velocity  of  Ag  as  found  in  these  salts  proves  to  be 
nearly  constant:  the  deviations  from  the  average  591 X108 
are  within  the  limits  of  the  probable  errors  of  observation, 
especially  as  the  latter  have  a  cumulative  effect.  We  con- 
sider this  an  additional  confirmation  of  the  recent  electrolytic 
hypotheses. 

This  average,  which  applies  for  25°,  may  be  considered  the 
true  value  for  the  velocity  of  the  Ag  ion,  within  a  few  thou- 
sandths, provided  Kohlrausch's  determination  of  the  limit  of 
conduction  for  argentic  nitrate  contains  no  important  error. 


290  MORRIS  LOEB 

We  can  now  calculate  the  ion's  velocity  at  0°,  from  the  values 
of  n  at  that  temperature  for  argentic  nitrate  and  pseudo- 
cumol-sulphonate  (Table  II),  and  [120]  the  values  of  X  re- 
duced from  Table  III  by  the  ratio  ^~  (Table  IV). 

A25 

1242  X  0.461  X  0.548  =  314 

842  X  0.727  X  0.517  =  317    Mean  =  315.5. 

We  again  call  attention  to  the  smallness  of  the  deviation. 
Now,  since  \=u+v,  we  can  obtain  the  velocities  of  all  our 
negative  ions,  by  subtracting  the  velocity  of  the  silver  from 
the  respective  conducting  powers.  In  Table  VI  we  find  on  the 
first  line  the  velocities  at  25°;  on  the  second,  those  at  0°;  on 
the  third,  the  coefficient  of  temperature  between  25°  and  0°, 
as  calculated  from  the  formula  v  =  v^[l+a(t-^5)],  a  being 
the  coefficient:  all  the  values  must  be  multiplied  by  the 
factor  given  in  the  final  column. 


x  io-8 

X  IO-8 

x  10-* 


X  10-8 
X  10-8 

x  10-* 

The  close  agreement  of  the  velocities  shown  in  line  I  with 
the  observations  of  the  rates  of  transfer  and  of  the  conduc- 
tion, is  proved  by  the  fact  that  the  calculated  and  observed 
values  agree  within  one  half  per  cent  in  all  cases.  A  glance  at 
Table  VI,  in  which  the  velocities  are  arranged  according  to 
magnitude,  will  bring  out  a  striking  relation  of  the  coefficients 
of  temperature.  The  coefficient  of  temperature  decreases  when 
the  velocity  increases.  We  may  add  that  the  coefficients  of 
temperature  for  the  monovalent  ions  OH  and  H,  which 


TABLE  VI 

C8HnS03 

CflH5S03 

C2H302. 

C2H5S04 

I. 

248 

318 

361 

368 

II. 

118 

156 

183 

III. 

210 

203 

197 

... 

C10H7S03 

C103 

Ag 

C104 

N03 

I. 

369 

587 

591 

621 

640 

II. 

180 

322 

316 

347 

364 

III. 

198 

181 

186 

177 

175 

KINETICS  OF  CERTAIN  SILVER  SALTS    291 

have  an  exceptionally  great  velocity,  can  be  added  to  this 

series.1 

OH  H 

I.  187  350  X  10-' 

III.  159  137  X  10-4 

A  result  of  this  regularity  would  be  that,  as  the  tempera- 
ture rises,  the  rates  of  transference  would  all  approach  the 
value  0.5,  and  the  conducting  powers  Xoo  of  all  salts  would 
approach  equality.2 

If  we  attempt  to  calculate  the  velocity  of  the  silver  ion 
from  [121]  the  salts  of  the  two  dibasic  acids  which  we  have 
studied,  we  obtain  from 

Ag2S2O6:  1540  X  0-394  =  0-607 
Ag2SiP6:  1120  X  0'534  =  0'598 

These  values  are  somewhat  greater  than  those  found  be- 
fore. To  avoid  a  conflict  with  the  necessary  assumption  that 
the  free  ion  of  silver  must  have  the  same  velocity,  no  matter 
whether  it  has  been  liberated  from  a  mono-  or  dibasic  acid 
ion,  we  must  admit  that  the  rates  of  transfer  in  these  two 
salts,  which  were  measured  at  a  concentration  0.025  and  0.028 
respectively,  must  change  on  further  dilution.  As  our  inves- 
tigation was  brought  to  a  close  by  the  departure  of  one  of  us 
from  Leipzig,  we  were  unable  to  set  this  question  at  rest;  we 
note  in  passing,  however,  that  the  dissociation  hypothesis 
makes  it  probable  that  the  compounds  of  multivalent  radicals 
are  still  undergoing  changes  at  dilutions  in  which  mono- 
basic compounds  show  a  constant  rate  of  transference.  The 
dissociation  products  for  Ag2S2O6,  for  instance,  are  Ag, 
AgS2O6  and  S2O6;  consequently  in  such  dilutions  as  0.025 
there  may  exist,  besides  the  ions  +Ag,  +Ag,  -S2O6,  upon 
which  we  based  our  calculations,  a  considerable  set  of  ions 
+Ag,  -AgS2O6;  if  these  decompose  on  further  dilution,  the 

1  Nernst,  Zeitschr.  2,  626.  2  Compare  Arrhenius,  loc.  cit.,  p.  45. 


292  MORRIS  LOEB 

rate  of  transference  must  continue  to  change.  We  have  here 
considerations  similar  to  those  which  Hittorf  used  so  skill- 
fully nearly  thirty  years  ago,1  in  obviating  the  difficulties 
which  the  abnormal  behavior  of  cadmic  iodide  threatened  to 
cast  in  the  way  of  his  theory. 

1  Hittorf,  Pogg.  Annalen,  106,  546  (1859). 


[300]    THE   USE   OF   THE   GOOCH   CRUCIBLE   AS 
A  SILVER  VOLTAMETER1 

FOR  the  exact  measurement  of  electric  currents,  no  method 
is  more  convenient  and  more  free  from  objections  than  the 
determination  of  the  amount  of  silver  deposited  from  a  neutral 
solution  of  a  silver  salt.  The  sole  source  of  error,  especially 
where  weak  currents  are  concerned,  arises  from  the  imperfect 
adhesion  of  the  silver  upon  the  cathode.  The  latter  is  gener- 
ally a  platinum  crucible,  and  the  silver,  except  for  densities 
of  current  not  always  attainable,  is  deposited  in  minute 
scales  and  needles,  instead  of  forming  a  coherent  coating. 
In  the  subsequent  washing  and  decantations,  those  par- 
ticles are  readily  detached  and  carried  away,  and  a  loss  is 
occasioned  which  becomes  very  appreciable  when  the  total 
deposit  does  not  exceed  a  few  centigrams.  A  Gooch  crucible, 
with  asbestos  felting  over  the  holes,  would  be  a  far  better 
form  of  cathode,  if  it  would  only  hold  the  solution  during 
electrolysis  without  leaking.  I  have  attained  this  very  satis- 
factorily, by  replacing  the  ordinary  platinum  cap  with  a  glass 
siphon  of  the  shape  indicated  in  Fig.  1. 


.  1.  FIG.  2. 

1  Reprinted  from  Journal  of  the  American  Chemical  Society,  12,  300  (1890). 


294  MORRIS  LOEB 

The  crucible  is  made  on  a  rather  taller  and  narrower  pattern 
than  is  usual,  and  it  fits  quite  snugly  into  the  upper  portion 
of  the  cup  [301]  of  the  siphon.  The  two  are  united  by  a  bit  of 
rubber  drawn  over  the  junction;  the  rubber  should  be  freed 
from  sulphur,  although  there  is  no  real  danger  of  contact  with 
the  silver  solution. 

The  apparatus  is  filled  with  the  silver  nitrate  solution,  so 
that  the  top  of  the  siphon  is  not  quite  reached  and  is  set  upon 
the  stand,  Fig.  2.  After  the  completion  of  the  electrolysis, 
adding  a  little  liquid  causes  the  siphon  to  act  and  to  drain 
off  every  drop  of  nitrate  solution,  without  in  any  way  dis- 
turbing the  deposit;  the  lixiviation  with  hot  water  is  equally 
expeditious,  and  the  crucible  can  then  be  detached  from  the 
siphon,  dried  and  weighed. 

The  stand  for  this  voltameter  is  seen  in  Fig.  2.  The  crucible 
is  hung  in  a  brass  block,  the  conical  hole  in  which  fits  exactly 
around  its  upper  third;  to  this  block  the  negative  wire  of  the 
circuit  is  to  be  attached. 

The  positive  wire  is  connected  with  a  long  horizontal  cone, 
which  is  isolated  from  the  cast-iron  base,  and  from  which  the 
silver  cone  that  forms  the  anode  is  suspended  within  the 
crucible  by  a  silver  wire. 


[145]    IS  CHEMICAL  ACTION  AFFECTED  BY 
MAGNETISM?  1 

THE  close  relationship  between  electricity  and  chemical 
affinity  on  the  one  hand,  and  that  between  electricity  and 
magnetism  on  the  other,  have  naturally  raised  the  question 
whether  any  relation  can  be  traced  between  affinity  and  mag- 
netism. 

This  question  was  the  subject  of  numerous  investigations 
during  the  entire  first  half  of  this  century,2  but  appears  to 
have  dropped  out  of  sight,  until  Professor  Remsen,3  in  1882, 
again  attracted  attention  to  it  by  the  interesting  observation 
that,  from  a  solution  of  the  sulphate,  copper  is  unequally  de- 
posited upon  the  armature  of  a  horse-shoe  magnet.  Other 
experiments  by  Messrs.  Nichols  and  Franklin,4  and  Messrs. 
Rowland  and  Bell,5  have  also  borne  relation  to  this  question. 
I  have  nevertheless  ventured  to  approach  the  subject  from  a 
new  side,  with  the  conviction  that  all  of  these  investigations 
introduce  phenomena  which  tend  to  obscure  the  point  of 
issue,  i.e.,  the  effect  of  magnetism  upon  the  chemical  reaction 
itself.  This  will  be  made  clear  by  an  analysis  of  the  principles 
upon  which  these  investigations  have  been  conducted;  they 
can  be  divided  into  four  categories. 

The  earliest  experiments  regarded  the  rusting  of  bar  mag- 
nets; and  the  most  trustworthy  observers  appear  to  invali- 
date the  assertion  of  a  few,  that  magnetized  iron  differs  from 

Reprinted  from  American  Chemical  Journal,  13,  145  (1891). 

For  full  literature  see  E.  Wartmann,  Philosophical  Magazine,  30,  266. 

American  Chemical  Journal,  3,  137. 

American  Journal  of  Science,  34,  419;  35,  290. 

Philosophical  Magazine,  34,  419;  35,  105. 


296  MORRIS  LOEB 

the  non-magnetized  [146]  metal  in  this  respect,  or  that  the 
north  and  south  poles  show  dissimilar  behavior.  The  experi- 
ments were  naturally  crude,  and  a  positive  result,  were  it  ad- 
mitted, would  obviously  have  been  due  to  a  polarized  ar- 
rangement of  the  molecules,  rather  than  to  variations  in 
chemical  affinity. 

Next  came  the  crystallization  of  salts  or  metals  from  a  so- 
lution, within  and  without  a  magnetic  field.  Quite  a  number 
of  observers  appear  to  have  found  that  the  direction  of  growth, 
either  of  the  crystals  themselves  or  of  the  clusters  which  they 
form,  can  be  affected  by  the  presence  of  a  magnetic  field, 
even  though  the  substance  be  a  diamagnetic.  But  what  is 
there  in  this  that  involves  a  modification  of  chemical  action? 
The  quantity  of  deposit  has  not  been  observed  to  be  altered 
by  the  magnet;  the  physical  arrangement  of  the  molecules 
during  crystallization  is  always  governed  by  directive  forces 
having  no  connection  with  affinity,  and  to  the  ordinary  ones 
is  now  superimposed  the  polarizing  influence  of  the  magnet. 

A  different  principle  is  involved  in  Remsen's  experiments, 
for  they  depend  upon  the  removal  of  particles  from  a  mag- 
netized mass  of  iron,  and  the  substitution  therefor  of  faintly- 
magnetic  copper.  The  explanation  of  Messrs.  Rowland  and 
Bell  must  appear  highly  plausible,  that  the  resistance  to  such 
removal  must  protect  the  more  highly  magnetized  points 
from  reaction,  so  long  as  there  are  places  where  the  iron  can 
be  more  readily  dissolved.  We  have  here  a  purely  mechanical 
reason  for  the  localization  of  the  reaction,  in  a  non-uniform 
field.  That  the  total  amount  of  reaction  would  not  be  affected 
we  may  infer  from  a  recent  experiment  by  Fossati,1  in  which  he 
shows  that  the  weight  of  iron  precipitated  from  a  solution  by 
zinc  is  not  affected  by  the  presence  of  a  strong  magnetic  field. 

1  Bolletino  delV  Elettrirista,  1890.  I  quote  from  Wiedemann's  Beibtttter,  1890,  p. 
1010,  which  alone  is  at  my  disposal. 


CHEMICAL  ACTION  AND  MAGNETISM    297 

Apparently  inconsistent  with  the  protection-hypothesis 
are  the  observations  of  Messrs.  Nichols  and  Franklin,  which 
show  that  iron  which  has  become  passive  through  the  action 
of  strong  nitric  acid  suddenly  regains  its  activity  when  intro- 
duced into  a  magnetic  field.  One  might  be  tempted  to  ascribe 
this  to  the  exposure  of  fresh  surfaces,  owing  to  the  rearrange- 
ment of  the  molecules  during  magnetization;  but  since  the 
investigators  have  reason  to  seek  the  cause  in  the  induction 
of  local  electric  currents  by  the  magnet,  [147]  we  may  assign 
this  phenomenon  to  the  fourth  category,  that  of  galvanic 
action  in  the  magnetic  field.  To  my  knowledge,  Messrs. 
Nichols  and  Franklin  were  the  first  to  experiment  upon  the 
effect  of  an  unequal  magnetic  field  upon  an  electrolyte:  the 
movement  of  the  paramagnetic  salt  to  the  interior  portions 
of  the  field,  and  the  inequality  of  electric  potential  consequent 
upon  the  variation  of  concentration,  were  proved,  as  might  be 
expected.  We  have,  then,  this  effect,  as  well  as  that  of  the 
Faradic  induction,  to  account  for  any  irregularities  which 
the  galvanoscope  might  indicate,  when  a  solution  undergoing 
electrolysis  was  also  subjected  to  magnetic  influence.  Messrs. 
Nichols  and  Franklin  do  ascribe  their  observations  to  this 
cause,  and  see  no  reason  to  introduce  a  supposed  change  of  the 
chemical  conditions. 

I  fail  to  see  any  significance  in  the  experiment  of  placing 
one  of  two  gas- voltameters,  or  one  of  two  cells  containing  an 
iron  solution,1  in  a  magnetic  field,  and  looking  for  a  difference 
in  the  amount  of  decomposition  when  a  current  is  passed 
through  the  couple  in  series.  Surely  no  such  result  could  be 
expected  in  the  face  of  the  universally  acknowledged  Law  of 
Faraday,  unless,  indeed,  a  magnetic  field  were  imagined  to 
alter  the  quanti valence  of  the  elements. 

To  sum  up :  all  experiments  hitherto  made  have  introduced 

1  Fossati. 


298  MORRIS  LOEB 

non-chemical  phenomena,  due  either  to  the  inequalities  of  the 
magnetic  field,  or  to  the  physical  heterogeneity  of  the  reacting 
system,  or  to  both  of  these  causes  at  once.  It  was  my  wish  to 
study  the  effect  of  magnetism  upon  chemical  reaction  where 
the  system  remained  homogeneous  throughout,  and  where  the 
field  of  stress  was  practically  homogeneous.  Such  conditions 
can  be  realized  by  observing  the  speed  of  some  reaction  which 
does  not  involve  solids,  in  the  presence  of  a  magnet,  and,  again, 
when  there  is  no  magnetic  effect,  provided  the  magnetic  prop- 
erties of  the  system  could  be  altered  by  the  reaction.  In  the 
same  manner  as  an  electric  system  is  affected  by  its  approach 
to  or  removal  from  a  magnetic  field,  we  might  suppose  that 
a  reaction  which  made  a  system  more  or  less  amenable  to 
magnetic  action  might  show  evidence  of  acceleration  or  re- 
tardation by  the  magnetic  force.  If  this  effect  were  appre- 
ciable, the  relation  between  magnetic  force  and  affinity  would 
be  established,  and  data  could  be  obtained  for  calculating  the 
real  value  of  magnetization. 

[148]  My  results,  however,  have  been  negative,  and  I  am 
led  to  believe  that  no  such  relation  exists,  unless  it  be  so  slight 
that  my  means  of  observation  have  been  inadequate.  Being 
confident,  however,  that  my  method  has  been  of  no  lower 
order  of  delicacy  than  those  hitherto  employed  in  connection 
with  the  subject,  I  do  not  hesitate  to  assert  that  the  interest- 
ing effects  which  have  been  noted  are  not  due  to  a  variation 
of  affinity  or  of  chemical  reaction  in  its  strictest  sense.  For 
this  reason  I  herewith  present  my  results :  — 

The  choice  of  material  for  my  investigation  was  rather 
limited:  of  all  compounds,  the  salts  of  the  iron  group  alone 
yield  markedly  paramagnetic  solutions;  furthermore,  Wiede- 
mann  has  shown  that  the  ordinary  form  of  reaction  between 
salts  does  not  affect  the  total  magnetism  of  the  system,  so  long 
as  it  involves  merely  an  interchange  of  acids.  But  there  is  a 


CHEMICAL  ACTION  AND  MAGNETISM    299 

marked  change  when  the  constitution  of  one  of  the  ingredi- 
ents is  altered:  the  atomic  magnetism  of  trivalent  iron  is 
25  per  cent  greater  than  that  of  the  same  element  in  the  fer- 
rous state.  I  resolved,  therefore,  to  study  the  effect  of  mag- 
netism upon  the  speed  of  oxidation  and  reduction  of  iron  salts 
in  solution  by  reagents  which  showed  but  a  feeble  magnetism 
by  themselves. 

Two  such  reactions  have  already  been  studied  under  ordi- 
nary conditions,  and,  inasmuch  as  the  methods  employed 
seemed  admirably  suited  to  my  purpose,  I  have  followed  them 
in  this  investigation. 

Dr.  J.  J.  Hood1  determined  the  speed  of  the  reaction 

6FeS04+KC103+3H2SO4=SFe2(SO4)3+KCl+3H2O, 

by  estimating  volumetrically  with  permanganate  the  amount 
of  ferrous  salt  remaining  unaffected  at  different  stages  of  the 
process. 

Meyerhoffer2  gives  one  series  of  observations  upon  the 

reaction 

2HI+2FeCl3=I2+2FeCl2+2HCl, 

in  which  case  the  iodine  which  had  been  set  free  could  be 
determined  with  starch  paste  and  sodic  thiosulphate. 

OXIDATION  OF  A  FERROUS  SALT 

I  had  at  my  disposal  a  large  Ruhmkorff  electro-magnet, 
with  cylindrical  iron  cores  ten  inches  long  and  three  inches 
thick.  [149]  With  the  poles  three  inches  apart,  and  with  a 
current  from  ten  storage  cells,  the  intensity  of  the  magnetic 
field  was  roughly  determined  at  10,000  c.  g.  s.  per  square- 
centimeter.  For  my  supply  of  electricity  I  am  indebted  to  the 
kindness  of  the  director  of  the  Physical  Laboratory,  Professor 
A.  A.  Michelson.  While  ten  cells  were  usually  employed,  I 

1  Philosophical  Magazine,  [5],  6,  371;  8,  121;  13,  419. 

2  Zeitschr.  2,  597. 


300  ;  MORRIS  LOEB 

sometimes  was  enabled  to  use  double  that  number,  and  in 
several  instances  obtained  the  current  directly  from  the  dy- 
namo, employing  as  full  a  current  as  the  apparatus  would 
safely  bear.  Because  the  results  were  always  virtually  identi- 
cal, no  pains  were  taken  to  determine  the  exact  strength  of 
the  magnetic  field,  but  18,000  c.  g.  s.  is  a  low  estimate  of  the 
maximum  reached. 

The  axes  of  the  cores  being  horizontal,  a  prismatic  battery 
cell,  2jx6X6  inches,  was  placed  between  the  poles  to  serve  as 
a  bath  of  constant  temperature.  It  was  therefore  protected 
from  direct  contact  with  the  poles  by  thin  layers  of  cotton 
batting,  and  was  traversed  by  a  rapid  current  of  water  from 
a  reservoir  whose  contents  were  kept  within  0.1°  C.  of  the 
desired  temperature. 

The  solutions  were  contained  in  a  sort  of  pocket-flask  of 
100  cc.  capacity,  an  inch  thick,  and  having  two  flat  sides  of 
circular  outline  three  inches  in  diameter.  This  flask  was  sus- 
pended in  the  bath  in  such  a  manner  as  to  be  just  between 
the  poles  of  the  magnet.  The  solutions  which  were  not  to  be 
subjected  to  the  influence  of  the  magnet  were  contained  in  a 
precisely  similar  flask,  and  the  water-bath  in  which  this  was 
placed  was  fed  by  the  overflow  from  the  first  mentioned  one. 
Where  it  was  not  feasible  to  observe  the  two  reactions  at  the 
same  time,  especial  care  was  taken  to  keep  the  temperature 
constant. 

The  following  solutions  were  employed :  a  one-third  molec- 
ular solution  of  potassium  chlorate,  a  one-half  molecular 
solution  of  sulphuric  acid,  a  one-half  molecular  solution  of 
ferrous  sulphate,  a  solution  of  potassium  permanganate  of 
which  12.5  cc.  corresponded  to  1  cc.  of  the  iron  solution.  The 
latter  was  made  from  crystallized  ferrous  sulphate,  with  a 
little  sulphuric  acid  and  an  excess  of  metallic  iron,  so  that 
it  was  very  nearly  neutral. 


CHEMICAL  ACTION  AND  MAGNETISM    301 

Proper  volumes  of  the  chlorate  and  the  acid  solutions  hav- 
ing been  run  into  the  flask  and  sufficient  water  to  make  the 
volume  80  cc.,  the  solution  was  allowed  to  acquire  the  temper- 
ature of  the  water-bath.  Thereupon  20  cc.  of  the  ferrous  sul- 
phate solution,  which  had  been  brought  to  the  same  tempera- 
ture, were  added  [150]  rapidly,  the  flask  was  vigorously  shaken, 
and  at  once  replaced  in  the  water-bath.  If  the  magnet  was  to 
be  employed,  its  electric  circuit  was  closed  at  this  time.  After 
the  expiration  of  a  few  minutes,  10  cc.  were  withdrawn  from 
the  flask  by  means  of  a  pipette,  and  were  quickly  run  into  a 
large  quantity  of  cold  water  contained  in  a  porcelain  dish, 
the  time  being  noted  when  the  pipette  was  emptied.  The  titra- 
tion  was  then  executed  as  rapidly  as  possible.  This  operation 
was  repeated  at  suitable  intervals,  until  the  solution  was  ex- 
hausted or  external  conditions  prevented  a  continuation  of 
the  observation.  Where  two  reactions  were  to  be  observed 
together,  the  second  solution  was  mixed  ten  minutes  after 
the  first,  the  same  interval  being  preserved,  as  nearly  as  might 
be,  throughout.  Owing  to  the  weakness  of  the  permanganate 
solution  and  to  varying  conditions  of  illumination,  my  titra- 
tions  have  a  probable  error  of  fully  ^  to  ^  cc.,  but  this  is  in  no 
unfavorable  proportion  to  the  observed  values;  in  cases  of 
over-coloration  I  rejected  the  result,  rather  than  titrate  back 
with  another  solution.  " 

The  reaction  has  been  proved  by  Hood  to  be  subject  to  the 
law 


at 

where  x—the  amount  of  substance  changed,  £=time  elapsed, 
A  and  B  represent  the  original  quantities  of  ferrous  sulphate 
and  chlorate  respectively,  and  C  is  a  coefficient  depending  on 
external  circumstances. 


302  MORRIS  LOEB 

As  equivalent  quantities  of  A  and  B  were  used, 

tj 
at 

Integrating,          -- —  =  C^+constant. 
A— x 

Calculating  this  constant  from  the  initial  conditions  d= 

#=0,  constant =—,  and  consequently 
A. 

x 


At    A-x 

A  is  the  amount  of  permanganate  required  at  the  first  titra- 
tion,  and  A  -x  represents  the  amount  of  each  subsequent  one, 
after  the  lapse  of  t  minutes.  We  possess  all  the  data  for  calcu- 
lating C.  This  coefficient  has  been  shown  by  Hood  to  depend 
upon  the  temperature,  to  be  augmented  by  the  presence  of 
free  [151]  acid,  and  diminished  by  the  presence  of  neutral 
salts  not  participating  in  the  reaction.  It  is  consequently 
decreasing  continually  during  the  reaction,  most  noticeably, 
however,  toward  the  end.  Furthermore,  if  magnetism  is  of 
influence,  the  values  of  C  must  show  it.  In  order  to  eliminate 
the  other  influences,  I  have  sought  to  take  the  samples  from 
corresponding  solutions  at  the  same  intervals  of  time,  and 
have  varied  the  conditions  somewhat  by  changing  the  tem- 
peratures as  well  as  the  amounts  of  sulphuric  acid  present  in 
different  series.1  It  will  be  seen  that,  while  there  is  consider- 
able variation  between  individual  determinations,  these  vari- 
ations are  no  greater  between  analogous  samples  of  two  cor- 
responding series  than  between  two  succeeding  samples  of 
the  same  series.  Further,  the  means  of  the  whole  series  agree 
well  with  each  other.  The  tables  which  I  subjoin  are  selected, 
solely  with  reference  to  their  general  reliability,  from  a  larger 

1  In  this  connection  it  may  be  interesting  to  note  that  this  reaction  is,  according  to 
my  experiments,  barely  perceptible  at  0°C.,  —  a  result  which  agrees  closely  with  the 
limit  set  by  Dr.  Hood  by  extrapolation  with  his  temperature-coefficient. 


CHEMICAL  ACTION  AND  MAGNETISM    303 

mass  of  material,  all  of  which  gave  analogous  results.  While 
the  effect  of  magnetism  should  produce  acceleration,  the 
variations  of  C  from  that  of  the  non-magnetic  reaction  are 
negative  quite  as  frequently  as  positive. 

Series  I.— KClOs+GFeSC^+SHaSC^.   Temperature,  10.2°, 
Series  II. — Same  conditions,  in  magnetic  field  (10  cells). 


0                        0                     24-38  24-26 

30-25               29-75               22-78  22-88  -049524  -048357 

105                    104-25                20-22  20-28  8050  7940 

155-17              154-86               18-71  18-68  8011  7951 

210                    210                      17-49  17-27  7695  7942 

241                    241-33                16-82  16-79  7546  7599 

305-25              305-5                  15-64  15-53  7491  7584 

Mean -048051  -047895 

Mean  of  last  five  .     .     .    -047758  -047803 

Series  III.  —  Same  relation,  KClOsiFeSCX;  great  excess 
H2SO4.  Temperature,  18.7°. 

Series  IV.  —  Same  as  III,  but  with  magnet  (20  cells). 

Series  V.  —  Same  as  III,  but  with  magnet  (dynamo). 
[152] 

t  A— x  C 


in  rv 


0              0  0  23-16  23-10  23-10  ...              

20  20  20-5  18-57  18-39  18-32  -035335  .035543     -035509 

40  40  40  15-33  15-45  15-41  5513  5358     ,     5400 

60  60  60]  13-28  13-38  13-21  5353  5241          5401 

80  80-5  80  11-71  11-58  11-42  5276  5348          5534 


100 

100-25 

100 

10-41 

10-45 

10-40 

5288 

5227 

5286 

120 

120 

120 

9-38 

lost 

9-45 

5282 

5211 

139-75 

130-75 

140 

8-72 

8-99 

8-54 

5116 

5197 

5272 

160-25 

155 

161 

7-94 

8-17 

7-84 

5164 

5104 

5233 

Mean 

•035292 

•035288 

•  035355 

REDUCTION  OF  FERRIC  CHLORIDE 

The  reaction  2HI+2FeCl3=l2+2FeCl2+2HCl,  is  not  a 
simple  one,  being  reversible,  and  furthermore  accompanied 
by  complicating  bye-reactions.  It  seemed  better  to  avoid  all 


304  MORRIS  LOEB 

attempts  to  obtain  the  reaction-coefficients,  and  to  make 
parallel  experiments,  with  exactly  the  same  time-intervals.  If 
the  magnetic  force  had  any  effect,  this  must  be  visible  from 
the  burette-readings. 

The  method  used  was  exactly  as  before,  but  diluted  solu- 
tions were  employed  to  prevent  the  loss  of  free  iodine.  Equiv- 
alent quantities  of  hydriodic  acid  and  ferric  chloride  were 

allowed  to  react  in  molecular  solutions,  and  10  cc.  were 

taken  out  at  a  time  and  titrated  with  -    -  "normal  sodium 

115 

thiosulphate  solution.  The  determinations  were  very  exact, 
and  the  corresponding  burette-readings  will  be  found  to  cor- 
respond so  closely  as  to  leave  no  doubt  of  the  exact  equality 
of  speed  within  and  without  the  magnetic  field.  I  give  all  the 
series  which  were  observed;  in  the  second  set,  the  reaction  was 
carried  as  far  as  it  would  go,  —  at  least  there  was  no  more 
iodine  liberated  after  15|  hours'  standing. 
Temperature,  17.8°. 

With  Magnet  (dynamo) 

Na2S2O3  required 

3-95 

4-52 

5-10 

5-401 

5-58 


With  Magnet  (dynamo) 

Na2S2O3  required 

5-92 
6-93 
7-38 
7-90 
8-04 

8-30 
8-28 


Without  Magnet  , 
Time                Na2S2O3  required 

\ 

Time 

30-5                    3-89 

30- 

60                       4-80 

60 

120                       5-10 

120 

180                       5-55 

180 

231                       5-60 

231 

[153]  Same  conditions. 

Without  Magnet 
Time                 NaaSzOs  required 

\ 

Time 

40                       5-99 

40 

86                       6-92 

85 

130                       7-38 

130 

205                       7-85 

205 

266                      8-07 

266 

325                      8-28 

325 

375                      8-32 

375 

, 

13301 

1  Without  magnet.     , 

CHEMICAL  ACTION  AND  MAGNETISM    305 

Same  proportions;  temperature,  0°. 

Without  Magnet  With  Magnet  (10  cells) 

Time  .NazSjOs  required  Time  Na-jSjOs  required 

60  2-70  60.5  2-80 

120  3-72  120  3-70 

195  4-54  195  4*42 

275  4-86  275  4  90 

360  5-20 

380  5-70  380  5-80 

480  6-06  480  6-10 

600  6-43  600  6-60 

705  6-71  705  6-75 


[263]  APPARATUS  FOR  THE  DELINEATION  OF 
CURVED  SURFACES,  IN  ILLUSTRATION  OF 
THE  PROPERTIES  OF  GASES,  ETC.1 

IN  attempting  the  graphic  representation  of  the  relations 
between  the  volume,  temperature  and  pressure  of  gases,  or  of 
other  problems  involving  three  variables,  one  is  met  by  the 
difficulty  of  properly  constructing  the  surfaces  in  question. 
Drawing  isothermals,  etc.,  as  projected  upon  a  single  plane, 
gives  a  very  imperfect  idea  of  the  actual  proportions.  For 
many  years  this  method  has  been  occasionally  supplanted  by 
the  actual  construction,  in  papier  mache  or  plaster,  of  models 
bounded  on  one  side  by  the  surface  in  question, — relief  maps, 
in  other  words.  This  plan  suffers  from  several  disadvantages. 
Aside  from  the  notion  of  solid  volume  which  is  involuntarily 
entertained  in  beholding  such  a  model,  some  of  the  surfaces 
are  too  complex  to  be  well  shown  in  this  manner.  Further- 
more, the  models  are  rather  hard  to  make,  expensive,  and 
occupy  a  good  deal  of  room. 

I  have  obviated  most  of  these  difficulties  by  obtaining  a  set 
of  glass  plates,  about  11  cm.  square  and  7  mm.  thick,  ruled  in 
squares  7mm.  wide.  Placed  one  on  top  of  the  other,  these  form 
a  block  whose  perpendicular  edge  may  be  taken  for  the  third 
axis  in  a  system  of  rectangular  coordinates.  Having  drawn 
upon  a  sheet  of  paper  the  curves  representing  the  relation 
between  volume  and  pressure  as  successively  0°,  10°,  20°,  30°, 
etc.,  of  temperature,  I  can  trace  them,  with  suitable  grease- 
chalks,  upon  the  successive  glass  plates.  When  these  are 

1  Reprinted  from  Journal  of  the  American  Chemical  Society,  13,  263  (1891).  Also 
Chemical  News,  66,  220  (1892). 


DELINEATION  OF  CURVED  SURFACES    307 

superposed,  the  curves  exhibit  the  proper  relations  in  space 
and  afford  a  very  fair  idea  of  the  nature  of  the  surface  of  which 
they  are  elements,  without  arousing  any  sensation  of  an  in- 
cluded volume.  Since  the  lines  can  always  be  erased  and  re- 
placed by  others,  a  set  of  twenty  plates  suffices  for  all  pur- 
poses, and  the  surfaces  can  be  produced  at  a  moment's  notice 
if  the  necessary  sketches  on  paper  are  preserved.  Besides 
[264]  being  useful  for  illustrating  lectures  in  molecular  phys- 
ics, the  plates  can  also  be  employed  to  advantage  in  the  con- 
struction of  crystallographic,  geological  and  other  models,  j 
Where  the  parallax,  inevitable  for  glass  plates,  becomes 
annoying,  it  is  possible  to  substitute  wide-meshed  cotton 
netting,  stretched  upon  square  frames  of  uniform  thickness. 
The  curves  can  be  embroidered  upon  the  net,  as  it  were,  with 
pieces  of  colored  thread;  although  it  is  not  quite  so  easy  to 
make  the  lines  conform  to  the  drawing,  the  general  effect 
remains  the  same. 


[1019]    NOTE  ON  THE  CRYSTALLIZATION 
OF  SODIUM  IODIDE  FROM  ALCOHOLS1 

AN  accidental  observation  during  the  preparation  of  some 
ethers  by  Williamson's  method  led  to  the  experiments  de- 
tailed below,  which  are  [1020]  merely  presented  as  an  addi- 
tion to  the  somewhat  restricted  literature  upon  the  addition 
products  between  haloid  salts  and  alcohols. 

Sodium  iodide  is  very  soluble  in  absolute  methyl  alcohol 
and  is  not  precipitated  therefrom  upon  the  addition  of  a  con- 
siderable volume  of  absolute  ether,  while  wet  ether  produces 
immediate  separation.  On  cooling  a  warm  solution,  rather 
large  plate-shaped  crystals  separate  out,  while  a  solution 
saturated  at  room  temperature  and  then  cooled  below  0° 
becomes  thoroughly  permeated  with  brilliant  white  felted 
needles;  although  differing  markedly  in  appearance,  these 
two  kinds  of  crystals  are  identical  in  composition. 

The  iodine  was  determined  by  Volhard's  method;  the 
methyl  alcohol,  by  heating  in  a  current  of  air  and  absorbing 
the  vapors  in  sulphuric  acid;  the  gain  in  the  weight  of  the 
latter  corresponding  accurately  to  the  loss  experienced  by  the 
crystals.  The  results  agreed  very  closely  with  the  formula 
NaI.3CH4O,  —  38.91  and  38.55  per  cent  of  methyl  alcohol 
and  51.50  per  cent  of  iodine  (calculated  for  NaI.3CH4O, 
39.06  and  51.58  per  cent). 

Potassium  iodide,  while  fairly  soluble  in  alcohol,  crystal- 
lizes free  from  it,  and  this  seems  to  be  quite  a  characteristic 
distinction  between  the  two  salts.  Sodium  iodide  crystallizes 
from  ethyl  alcohol,  forming  an  addition  product,  although  not 

1  Reprinted  from  Journal  of  the  American  Chemical  Society,  27,  1019  (1905). 


CRYSTALLIZATION  OF  SODIUM  IODIDE    309 

quite  so  readily  as  with  the  methyl  alcohol.  The  analysis 
gave  64.29  per  cent  I;  calculated  for  NaI.C2H6O,  64.91  per 
cent.  This,  therefore,  seems  to  be  the  formula  of  the  addition 
product  with  ethyl  alcohol. 

Normal  propyl  alcohol  dissolves  nearly  one-third  of  its 
weight  of  sodium  iodide  and,  on  evaporation  at  low  tempera- 
tures, deposits  crystals  which  appear  to  have  the  formula 
5NaI.3C3H8O,  as  two  distinct  preparations  gave  68.26  per 
cent,  and  68.22  per  cent  of  iodine,  against  68.27  per  cent  re- 
quired by  theory.  Apparently,  therefore,  the  molecular  pro- 
portion of  alcohol  assimilated  decreases  as  the  series  ascends. 


THE  VAPOR  FRICTION  OF  ISOMERIC  ETHERS1 

THE  recorded  experiments  on  the  friction  of  vapors,  by  the 
transpiration  method,  having  been  made  with  cumbersome 
apparatus  and  at  the  temperature  corresponding  to  the  boil- 
ing points  of  the  substances,  it  was  thought  important  to 
devise  a  method  whereby  non-saturated  vapors  could  be 
studied  at  identical  temperatures,  for  the  purpose  of  ascer- 
taining whether  the  constitution  as  well  as  the  composition 
of  organic  compounds  influences  the  molecular  volume,  of 
which  the  vapor-friction  is  a  function. 

The  apparatus  used  consists  of  a  U-tube,  one  limb  of  which, 
about  60  cm.  long,  has  a  bore  of  less  than  one  tenth  of  a  milli- 
meter, while  the  bend  and  the  other  limb  is  just  wide  enough 
to  allow  a  column  of  mercury  to  descend  unbroken.  A  stop- 
cock and  funnel-end  are  placed  on  the  wider  tube,  which  also 
bears  two  marks  about  50  cm.  apart.  The  capacity  of  the  tube 
between  these  marks  is  accurately  determined.  The  whole 
apparatus  can  be  heated  uniformly,  as  it  is  surrounded  by  a 
vapor-jacket.  Before  heating,  the  liquid  to  be  studied  is 
poured  into  the  tube  and  is  vaporized  as  the  temperature 
rises,  in  such  a  manner  as  to  expel  all  air  and  foreign  gases. 
A  short  column  of  mercury,  of  known  length,  is  introduced 
by  means  of  the  stop-cock,  and  in  its  descent  forces  the  vapor 
through  the  capillary;  the  time  in  which  the  lower  meniscus 
travels  from  the  upper  to  the  lower  mark  is  ascertained  by 
means  of  a  stop-watch.  The  method  is  easy  and  rapid,  and 
experiments  with  air  gave  results  agreeing  well  among  them- 
selves and  with  the  values  obtained  by  the  majority  of  previ- 

1  In  collaboration  with  F.  S.  M.  Peterson.    Reprinted  from  Science,  21, 818  (1905). 


VAPOR  FRICTION  OF  ETHERS         311 

ous  observers.  The  calculations  were  made  according  to  Poi- 
seulle's  formula,  very  few  corrections  being  necessary. 

From  the  study  of  isomeric  ethers,  as  well  as  ethyl  alcohol, 
it  was  found  that  the  constitution  has  a  decided  influence 
upon  the  internal  friction  of  the  vapor,  as  will  be  seen  from 
the  following  table,  representing  in  each  case  the  average 
of  a  number  of  experiments.  The  last  column  gives  the  com- 
parative volumes  of  the  molecules  according  to  the  formula 
suggested  by  L.  Meyer,  in  which  Y  is  the  friction,  M  the 
molecular  mass.1 


Substance                                                         Y  V 

Methyl  ether,  (CH3)2O 1133-5  55-53 

Ethyl  alcohol,  C2H6O 1100  58-09 

Methyl-ethyl  ether 1030  78-2 

Ethyl-ether 944-7  110-4 

Methyl-propyl  ether 951-8  100-74 

Methyl-isopropyl  ether 992-3  96-46 

Ethyl-propyl  ether 874-9  133-2 

Di-propyl  ether 797-6  170-7 

Di-isopropyl  ether 841-5  157-8 

1  The  editor  has  been  unable  to  find  the  original  source  of  this  equation,  which 
is  doubtless  of  a  highly  hypothetical  nature. 


[652]    ANALYSIS  OF  SOME  BOLIVIAN  BRONZES J 

THROUGH  the  kindness  of  the  authorities  of  the  American 
Museum  of  Natural  History,  we  were  enabled  to  analyze  por- 
tions of  certain  implements  collected  in  the  region  around 
Lake  Titicaca.  It  will  be  seen  that  these  metals  differ  remark- 
ably in  composition,  and  indicate  the  possession  of  consider- 
able metallurgical  skill  by  the  inhabitants  of  that  region. 
The  absence  of  the  slightest  traces  of  silver  may  be  taken  as  a 
proof  that  the  tin  was  derived  from  cassiterite,  rather  than 
native  tin.  The  composition  of  Specimen  IV  suggests  its 
preparation  from  domeykite,  or  some  other  copper  arsenide, 
fairly  free  from  sulphur.  Owing  to  the  small  mass  of  samples, 
which  were  drilled  or  cut  from  the  specimens,  the  density 
determinations,  made  with  water  in  a  pycnometer,  are  only 
approximate.  In  Specimen  VI  the  porosity  of  the  material 
undoubtedly  occasioned  a  low  result.  Tin  and  copper  were 
separated  by  potassium  [653]  polysulphide,  the  former  deter- 
mined as  stannic  oxide  and  the  latter  electrolytically.  Ar- 
senic was  separated  from  copper  by  Crookes's  method,  and 
sulphur  was  weighed  as  barium  sulphate  after  oxidation  with 
nitric  acid  in  a  sealed  tube. 

I.  Museum  No.  1842.   Small  chisel  or  pinch-bar,  18 X l| xj 
inches.  Very  tough.  Density,  8.68. 

II.  Museum  No.  B-1840.    Implement  5-6  inches  long, 
very  hard  and  tough;  pale  color.   Density,  8.94. 

III.  Museum  No.  1959.  Thick  wide  chisel  4|  inches  long, 
tough  but  less  hard.  Density, %8.92. 

1  In  collaboration  with  S.  R.  Morey.    Reprinted  from  Journal  of  the  American 
Chemical  Society,  32,  652  (1910). 


ANALYSIS  OF  SOME  BOLIVIAN  BRONZES   313 

IV.  Museum  No.  1-859.    Socketed  spear-head,  12  inches 
long.  Density,  8.89. 

V.  Museum  No.  2413.   Fragment  of  pointed  bar  6  inches 
long.   Density,  8.61. 

VI.  Museum  No.  1949.  Small  cast  chisel;  contained  char- 
acteristic air-holes  or  "pipes."    Apparently  contained  con- 
siderable oxide.  Density,  8.18  (?). 


Cu.. 
Sn  

ANALYSIS 
I              II            III             IV 

.  .  .  .  91.81         90.51         95.59         97.43 
.  .  .      7.56           8.92           4.48         

V             VI 

94.96         91.43 
4.98           7  05 

Pb 

tracef?) 

Fe.  .. 

trace         trace         trace         trace 

trace 

s 

trace                           little 

053 

As 

2.14 

99.37    99.43   100.07    99.57   100.47    98.48 

To  this  report  may  be  added  the  record  of  an  analysis,  made 
in  1901,  by  Dr.  A.  E.  Hill  with  one  of  us,  of  a  figurine  found 
in  Honduras.  Color,  pale  yellow;  density,  8.94-6.  Cu.  93.19, 
Sn  1.64,  Pb  1.60,  Fe  0.40  per  cent;  Au,  Sb  and  Zn  absent. 


[601]    STUDIES  IN  THE  SPEED  OF  REDUCTIONS  1 

FOR  some  years  past,  I  have  been  conducting  experiments 
to  ascertain  whether  certain  phenomena  due  to  the  mixture 
of  derivatives  of  closely  allied  bases  might  not  indicate  the 
formation  of  complex  bases  of  a  higher  order,  similar  to  the 
well-known  complex  acids.  The  difference  in  the  colloidal  ten- 
dencies of  mixed  and  pure  basic  salts,  the  appearance  of  spec- 
troscopic  lines  in  a  mixture  of  oxides,  none  of  which  emit  these 
lines  in  a  pure  state,  the  curious  relation  of  thorium  and 
cerium  with  respect  to  incandescence,  are  among  the  phe- 
nomena which  might  call  for  such  an  explanation.  While  my 
experiments  have  so  far  failed  to  yield  positive  evidence  in 
this  direction,  I  have  obtained  certain  results  which  seem 
worth  recording  for  their  own  sake. 

My  first  attempts  concerned  themselves  with  the  possible 
formation  of  an  aluminic-ferric  complex,  by  the  hydrolysis 
of  the  mixed  chlorides.  Solutions  representing  systematic 
variations  in  concentration  and  relative  proportion  of  ferric 
and  aluminic  hydroxides  were  observed  for  several  years  and 
finally  analyzed,  with  the  result  that  I  am  convinced  that  no 
aluminum  is  carried  down  permanently  combined  with  basic 
ferric  chlorides.  Any  temporary  occlusion  is  compensated  on 
standing  with  the  supernatant  acid  solution  of  ferric  chloride. 

But  a  complexity  of  these  two  bases  might  be  indicated, 
if  the  behavior  of  ferric  chloride  toward  reducing  agents 
were  affected  by  aluminic  chloride,  especially  since  the  latter 
would  hardly  be  likely  to  figure  as  a  chlorine-carrier  in  dilute 
solutions.  When  these  experiments  yielded  a  positive  result, 

1  Reprinted  from  Orig.  Com.  Eighth  International  Congress  of  Applied  Chemistry, 
26,  601  (1912). 


THE  SPEED  OF  REDUCTIONS  315 

other  chlorides  were  mixed  with  ferric  chloride  to  test  their 
effect  upon  its  stability  toward  reducing  agents.  The  method 
followed  closely  that  employed  by  A.  A.  Noyes,  in  studying 
the  speed  of  reaction  between  ferric  chloride  and  stannous 
chloride.  He  mixed  dilute  [602]  solutions  of  these  two  salts 
in  equivalent  proportions,  drew  measured  samples  from  time 
to  time,  running  them  into  a  solution  of  mercuric  chloride, 
to  arrest  the  reaction  by  removing  all  the  remaining  stannous 
chloride  without  affecting  the  trivalent  iron;  then  determin- 
ing the  amount  of  the  latter  by  titration  with  potassium 
dichr ornate.  Using  twentieth  normal  solutions  of  these  two 
compounds,  I  obtained  constants  for  the  reaction  agreeing 
closely  with  Noyes's  figures ;  upon  adding  aluminic  chloride, 
also  in  twentieth  normal  concentration,  the  speed  was  more 
than  doubled;  while  it  was  quadrupled  in  the  presence  of  a 
tenth  normal  solution  of  aluminic  chloride.  Of  course,  such 
a  result  might  be  ascribed  to  the  excess  of  chlorine  ions 
present,  especially  as  Noyes  had  found  that  hydrochloric  acid 
has  an  effect,  though  of  a  different  kind.  If  so,  chlorides  of 
divalent  elements  should  not  have  so  great  an  effect:  yet 
1/20  normal  solutions  of  manganous  chloride  and  of  glu- 
cinic  chloride  also  double  the  speed  of  reduction,  although 
the  ionization  cannot  be  the  same.  A  1/20  normal  solution 
of  quadrivalent  thorium  does  not  accelerate  quite  as  much. 
As  is  well  known,  Noyes  considers  this  as  a  typical  reaction 
of  the  third  order,  and  shows  that  his  equation 


c  =  l(   l      M 

2AU-.302   A2/ 


applied  to  his  experimental  data,  gives  a  fairly  constant  value 
for  Ca.  My  series,  which  I  cannot  reproduce  in  full,  show  about 
the  same  degree  of  constancy  for  €3.  Consequently,  I  think  it 
fair  to  assume  that  the  reaction  remains  of  the  same  type, 


316  MORRIS  LOEB 

and  that  the  variations  in  speed  are  due  to  the  specific  in- 
fluences of  the  metals  concerned.  For,  as  will  be  seen,  the 
accelerations  are  not  exactly  the  same.  I  give  average  values 
of  c3,  always  for  the  reaction  between  1/20  normal  ferric 
and  stannous  chlorides. 

C3 

Without  admixture  67-8 

With  1/20  A1C13  149-6 

With  1/20  MnCl2  161-2 

With  1/20  G1C12  159-4 

[603]                  With  1/20  ThCl4  157-0 

With  1/10  Aids  288-1 

With  1/10  MnCl2  266-4 

With  1/20  SnCl4  225-0 

With  1/40  SnCl4  131-0 

The  last  two  values  are  anomalous;  but  expectedly  so,  as 
this  compound  enters  into  the  original  reaction. 

Noyes  has  found  that  the  addition  of  free  hydrochloric 
acid  alters  the  nature  of  the  reaction,  so  that  it  becomes 
one  of  the  second  order.  I  find  that  several  chlorides,  nota- 
bly zirconium  chloride  and  oxy chloride,  have  a  similar  effect. 
The  reason  must  be  different  from  Noyes's  explanation,  based 
on  free  chlorine  ions. 

Another  series  of  experiments,  with  the  same  fundamental 
object,  sought  to  study  the  influence  of  analogous  compounds 
on  eerie  sulphate.  Cerium,  alone  of  the  so-called  rare-earth 
group,  lends  itself  to  studies  in  oxidation  and  reduction, 
although  virtually  no  work  has  been  done  in  following  these 
changes  quantitatively.  Of  the  salts  of  the  tetravalent  base, 
only  the  sulphate  is  stable  in  aqueous  solution,  and  then  only 
in  the  presence  of  much  free  acid.  On  standing,  its  orange 
color  fades  very  slowly,  a  marked  odor  of  ozone  indicating 
the  by-product  of  its  reduction  to  the  cerous  state.  Indeed, 
I  am  doubtful  whether  I  have  ever  had  a  solution  of  the 
tetravalent  salt,  free  from  any  trivalent  admixture.  After 
many  trials  I  found  that  a  fair  idea  of  a  reduction  speed  might 


THE  SPEED  OF  REDUCTIONS         317 

be  obtained  by  mixing  cerium  sulphates  and  glucose  in  equi- 
molecular  amounts  in  dilute  solution,  maintaining  at  25°  C., 
and  titrating  samples  with  very  dilute  hydrogen  dioxide  solu- 
tion, which  instantaneously  completes  the  decolorization  of 
the  eerie  salt.  The  reaction  with  glucose  is  completed  in  about 
two  hours  and  can  be  readily  followed  in  15-minute  intervals. 
Of  course,  the  stability  of  the  hydrogen  peroxide  standard 
was  meanwhile  controlled  with  permanganate  solution. 

For  some  unexplained  reason,  the  reaction  as  studied  by 
me  does  not  follow  a  logarithmic  law:  the  amount  of  cerium 
reduced  is  simply  proportionate  to  the  elapsed  time,  so  that 
x/t  is  pretty  nearly  constant  for  every  individual  series.  So 
anomalous  a  [604]  behavior  naturally  precludes  any  claim 
on  rigid  deduction.  But  the  experiments  had  comparative 
values,  when  they  were  compared  with  others,  in  which  equiv- 
alent quantities  of  lanthanum  sulphate  and  thorium  sulphate 
had  been  mixed  with  the  solution  of  cerium  salts. 

Values  of  x/Wt 

Pure  eerie  solution  694.8,693.1, 

With  thorium  708,697 

With  lanthanum  665.1,658.1 

Here  again,  the  influence  of  the  cognate  metal  seems  un- 
mistakable and  distinctive.  My  only  explanation  lies  in  the 
complexity  of  the  base,  although  I  admit  that  the  evidence, 
so  far,  is  not  conclusive. 


APPENDIX 


LABORATORY  MANUAL1 

LIST  OF  APPARATUS  FURNISHED  FOR  THIS  COURSE 

1  Notebook,  1  Bent  ignition  tube, 

1  Manual,  2  Glass  rods, 

1  Pipestem  triangle,  1  Meter  glass  tubing, 

1  File,  2  Watch-glasses, 

1  Horn  spatula,  2  Rubber  stoppers, 

1  Steel  forceps,  2  Cardboard  boxes. 

Test-tube  holder,  1  Package  filters, 

Test-tube  brush,  10  cm.  black  rubber  tube, 

Wire  gauze,  1  10  cm.  graduated  cylinder, 

Porcelain  dish,  1  Box  of  weights, 

Porcelain  crucible,  1  Pair  of  scales, 

Porcelain  lid,  1  Towel. 

Glass  U-tube, 

Bunsen  burner,  12  Test-tubes, 

Hose  for  same,  2  Funnels, 

1  Star  for  same,  1  Long-stemmed  funnel, 

1  Chimney  for  same,  1  200  cc.  flask, 

1  Wing-top  for  same,  1  750  cc.  flask, 

2  Iron  rods,  1  Set  wash-bottle  fittings, 
2  Iron  rings,  3  Small  beakers, 

1  Pneumatic  trough,  2  Common  bottles,  small, 

1  Test-tube  rack,  1  Common  bottle,  large. 

This  apparatus  is  loaned  to  the  student  on  the  distinct  understanding  that  it 
remains  the  property  of  the  laboratory.  It  must  not  be  carried  away,  nor  put  to 
improper  uses.  Each  student  is  held  responsible  for  the  apparatus  issued  to  him,  and 
will  be  obliged  to  return  the  apparatus  clean  and  in  good  condition  when  surrender- 
ing his  desk,  or  pay  for  what  is  missing. 

Compare  the  above  list  carefully  with  the  apparatus  in  your  desk.  Call  attention 
to  any  imperfections  and  satisfy  yourself  that  nothing  is  missing.  Do  not  leave  any 
apparatus  outside  your  drawer  and  cupboard,  when  leaving  the  laboratory,  and  see 
that  the  drawer  is  fastened  and  the  cupboard  locked. 

When  the  desk  is  surrendered,  all  apparatus  which  is  returned  clean  and  in  good 
condition  will  be  credited  in  full;  pieces  which  are  dirty  or  damaged,  but  still  fit 
for  some  use,  will  be  credited  at  half  price.  Particular  attention  is  called  to  the  neces- 
sity of  taking  good  care  of  the  weights  and  balances. 

HYDROGEN 

To  generate  this  gas :  —  After  convincing  yourself  that  the 
generating  apparatus  does  not  leak,  remove  the  cork,  and  put 

1  Prepared  for  students  in  Elementary  Inorganic  Chemistry  at  New  York  Uni- 
versity. 


322  APPENDIX 

sufficient  granulated  zinc  into  the  bottle  to  completely  cover  the 
bottom.  Replace  the  cork,  pour  enough  water  into  the  bottle  to 
seal  off  the  lower  end  of  the  funnel-tube.  Add  strong  hydrochloric 
acid,  a  little  at  a  time,  and  in  such  a  manner  that  air-bubbles  shall 
not  be  carried  down  with  it.  Whenever  the  evolution  of  the  gas 
becomes  less  brisk,  more  acid  should  be  added. 

CAUTION:  No  flame  should  be  allowed  anywhere  near  a  hydrogen  generator 
until  gas  has  been  evolving  briskly  for  at  least  five  minutes  ! !  Do  not  actually  apply 
a  flame  to  any  portion  of  the  apparatus,  until  a  test,  according  to  Exp.  1,  shall  have 
proved  the  absence  of  an  explosive  mixture  ! 

EXPERIMENT  1.  To  test  whether  air  has  been  entirely  displaced 
by  hydrogen:  —  Pour  so  much  water  into  the  "pneumatic  trough  " 
that  the  perforated  shelf  is  well  covered.  Immerse  a  test  tube  until 
it  is  quite  full  of  water;  raise  the  closed  end  out  of  the  water,  and 
rest  the  tube  with  its  opened  end  upon  the  shelf.  Bring  the  delivery- 
tube  of  the  gas  generator  into  such  a  position  that  the  escaping 
bubbles  rise  into  the  test-tube  and  displace  the  water  contained  in 
it.  When  the  tube  is  quite  full  of  gas,  close  it  with  your  thumb  and 
carry  it  to  a  lighted  burner,  not  removing  your  thumb  until  the 
mouth  of  the  tube  is  close  to  the  flame.  If  the  gas  lights  with  a  faint 
sound,  and  the  flame  works  its  way  quietly  down  the  tube,  no  air 
was  mixed  with  the  hydrogen  in  the  generator;  but,  if  the  gas 
burns  all  at  once,  with  more  or  less  of  an  explosion,  air  was  still  con- 
tained in  the  generator  at  the  time  the  sample  was  taken.  Repeat 
the  experiment,  until  a  sample  burns  quietly. 

NOTE  that  this  experiment  must  be  repeated  every  time  that  the  generator  is  set 
up  afresh.  The  small  volume  and  the  thin  walls  of  the  test-tubes  make  these  ex- 
plosions harmless,  whereas  a  similar  explosion  in  the  generator  might  lead  to  danger- 
ous injuries. 

EXP.  2.  To  compare  the  density  of  hydrogen  with  that  of  air. 
Fill  two  test-tubes  over  the  pneumatic  trough  with  hydrogen: 
hold  one,  mouth  up,  for  ten  seconds,  then  approach  the  mouth 
to  the  flame;  hold  the  other,  mouth  down,  for  ten  seconds,  and 
approach  to  the  flame.  Note  and  explain  any  difference. 

EXP.  3.  Connect  the  inner  tube  of  the  "osmose-apparatus" 
with  the  hydrogen  generator,  by  means  of  a  bit  of  rubber  tube. 
The  pipe-bowl  will  be  filled  with  hydrogen  in  a  little  more  than  two 
minutes.  Pull  out  the  inner  tube  and  set  the  open  end  of  the  outer 


APPENDIX  323 

tube  under  water.   Observe  what  happens,  and  ask  for  an  oral  ex- 
planation. 

EXP.  4.  If  a  test-tube  is  only  partially  filled  with  water,  closed 
and  inverted  with  its  mouth  under  water,  hydrogen  being  then 
introduced,  a  mixture  will  be  formed  of  the  air  left  in  the  tube, 
with  the  volume  of  hydrogen  represented  by  the  quantity  of  water 
originally  placed  in  the  tube.  Fill  four  test-tubes  one-quarter,  one- 
third,  one-half,  and  two-thirds,  respectively,  full  of  water;  invert 
in  pneumatic  trough,  displace  the  water  with  hydrogen;  close  with 
thumb,  carry  to  flame  and  compare  violence  of  explosions. 

EXP.  5.  Dry  the  end  of  the  delivery-tube  with  a  bit  of  filter- 
paper.  Allow  the  gas  to  flow  upon  bits  of  moist  litmus  paper,  red 
and  blue :  note  whether  their  color  is  affected. 

EXP.  6.  Wipe  a  beaker  clean  and  dry;  then  hold  it  for  a  min- 
ute or  more  over  the  mouth  of  the  delivery-tube  and  note  whether 
anything  is  deposited  upon  the  beaker.  Light  the  hydrogen  as  it 
issues  from  the  tube,  and  again  hold  the  beaker  over  the  jet. 

EXP.  7.  Fill  a  small  bottle  with  hydrogen  over  the  pneu- 
matic trough.  Lifting  the  bottle,  mouth  down,  out  of  the  trough 
with  your  left  hand,  push  a  lighted  match  well  up  into  it,  holding 
the  match  by  means  of  the  steel  forceps,  with  your  right  hand. 

EXP.  9.  Disconnect  the  generating  apparatus,  and  filter  its 
liquid  contents  into  an  evaporating  dish,  being  careful  not  to  fill 
the  latter  above  the  lip;  the  superfluous  liquid  may  be  thrown  away 
and  any  undissolved  zinc  can  be  left  in  the  generator,  for  future 
use.  The  small  stove  in  the  draught-closet  is  lighted,  the  porcelain 
dish  set  upon  it  and  heated  with  a  small  flame  until  the  liquid  has 
all  evaporated.  As  this  operation  takes  some  time,  and  requires 
little  attention,  it  can  be  conducted  during  the  progress  of  some 
of  the  succeeding  experiments. 

Write  the  equation  which  expresses  the  action  of  hydrochloric  acid  upon  zinc. 

OXYGEN 

EXP.  10.  Heat  about  one  gram  of  potassium  chlorate  in  a 
clean,  dry  test-tube,  being  careful  not  to  allow  the  flame  at  any  time 
to  strike  that  portion  of  the  tube  which  is  above  the  substance,  since 


324  APPENDIX 

this  is  apt  to  cause  the  tube  to  break.  When  the  salt  has  melted 
and  a  brisk  evolution  of  gas  is  taking  place,  hold  a  glowing  splin- 
ter of  wood  to  the  mouth  of  the  tube.  Heat  the  fluid  salt  until  no 
more  gas  is  seen  to  be  given  off,  and  then  set  aside  to  cool  (proceed- 
ing meanwhile  with  Exps.  11  and  12).  When  the  tube  is  quite  cold, 
add  some  distilled  water  and  warm,  until  a  portion  of  the  fused 
mass  has  dissolved.  Filter  the  solution  into  a  clean  test-tube,  add 
two  drops  of  nitric  acid  and  five  drops  of  a  solution  of  silver  nitrate. 

EXP.  11.  Dissolve  about  one-fourth  gram  of  potassium  chlorate 
in  distilled  water  and  add  two  drops  of  nitric  acid;  then  five  drops 
of  silver  nitrate. 

EXP.  12.  —  Dissolve  about  one-fourth  gram  of  potassium 
chloride  in  distilled  water  and  add  two  drops  of  nitric  acid;  then  five 
drops  of  silver  nitrate. 

What  is  the  behavior  of  potassium  chlorate,  and  of  potassium  chloride,  respec- 
tively, toward  nitric  acid?  toward  silver  nitrate?  If  a  precipitate  forms, 
what  must  it  be  ?  What  conclusion  can  be  drawn  as  to  the  nature  of  the  solu- 
tion obtained  in  Exp.  10  ?  Write  the  equation  expressing  the  result  of  heating 
potassium  chlorate. 

EXP.  13.  Clean,  dry  and  weigh  a  porcelain  crucible  and  lid. 
Add  about  one  gram  of  potassium  chlorate  to  the  crucible,  and  re- 
weigh  exactly.  The  difference  between  the  first  and  second  weigh- 
ings will  give  the  precise  amount  of  salt  used.  Set  the  crucible 
upon  a  pipe-stem  triangle,  supported  on  an  iron  ring  and  stand, 
and  heat  gradually  with  a  Bunsen  burner,  until  all  the  oxygen  has 
been  expelled.  This  can  be  done  without  any  danger  of  loss  from 
spattering,  if  the  heating  is  conducted  uniformly  and  slowly.  When 
the  salt  is  in  quiet  fusion,  allow  the  crucible  to  cool  to  room  tempera- 
ture, then  weigh.  The  loss  of  weight  will  indicate  the  quantity  of 
oxygen  driven  off.  How  much  oxygen  is  contained  in  one  hundred 
parts  of  potassium  chlorate? 

EXP.  14.  To  ascertain  the  density  of  oxygen  gas.  The  appa- 
ratus furnished  for  this  experiment  consists  of  a  tube  filled  with  a 
mixture  of  potassium  chlorate  and  black  oxide  of  manganese  —  for 
generating  oxygen,  —  a  U-tube  containing  strong  sulphuric  acid, 
and  a  delivery  tube.  The  U-tube  serves  to  prevent  the  escape  of 
everything  but  oxygen.  Place  this  apparatus,  with  the  exception 


APPENDIX  325 

of  the  delivery-tube  and  its  stopper,  upon  one  pan  of  the  balance, 
and  exactly  counterpoise  it  with  sand,  poured  into  a  beaker  upon 
the  other  pan.  This  counterpoise  must  not  be  disturbed  until  the 
experiment  has  been  completed.  Connect  the  apparatus  up  with  a 
delivery-tube  and  support  it  so  that  the  heating-tube  is  in  a  slanting 
position,  while  the  end  of  the  delivery-tube  dips  under  the  mouth  of 
a  large  bottle  filled  with  water,  and  set  inverted  upon  the  shelf  of 
the  pneumatic  trough.  Gradually  heat  the  mixture  in  the  tube, 
holding  the  burner  in  your  hand,  and  keeping  the  flame  brushing 
along  the  tube.  Once  heating  is  commenced,  it  must  not  be  inter- 
rupted until  no  more  gas  is  seen  to  leave  the  delivery-tube :  remove 
the  latter,  with  its  stopper,  from  the  U-tube;  and  then  take  away  the 
flame  and  allow  the  apparatus  to  grow  cold.  (Removing  the  flame 
before  the  delivery-tube  was  disconnected  might  cause  water  to  rise 
back  into  the  apparatus,  owing  to  the  contraction  of  the  cooling 
gas.)  When  the  apparatus  is  cold,  place  the  same  parts  upon  the 
balance  pan,  as  before:  but  a  certain  amount  of  weights  must  be 
added  to  this  pan,  to  bring  it  into  equilibrium  with  the  original 
counterpoise.  This  weight  should  be  noted,  as  it  represents  the  mass 
of  oxygen  which  has  been  transferred  from  the  tube  to  the  bottle. 
We  must  now  proceed  to  measure  the  volume  occupied  by  this 
mass.  Note  the  temperature  of  the  air  near  the  bottle.  Raise  the 
bottle  slightly  from  its  shelf,  slip  a  piece  of  smooth  paper  under  its 
mouth,  and  invert  dexterously,  without  spilling  any  of  the  water 
from  the  bottle.  No  effort  need  be  made  to  retain  the  oxygen,  as 
its  volume  is  indicated  by  the  contents  of  the  bottle  above  the 
water  level.  Fill  the  bottle  brimful  from  a  measuring-glass,  being 
careful  to  ascertain  the  number  of  cubic  centimeters  of  water  re- 
quired to  complete  the  filling,  as  they  represent  the  volume  of  oxy- 
gen at  the  temperature  of  the  room,  t°.  To  reduce  this  volume  to 

O^Q 

0°,  multiply  it  by  the  fraction  -       —  • 

273 +2 

Knowing  the  volume  and  the  mass  of  the  oxygen  produced  in 
this  experiment,  calculate  the  weight  of  one  liter  of  oxygen  gas. 

RELATIONS  OF  COMBINING  WEIGHTS 

EXP.  15.  Weigh  a  clean  watch-glass,  place  about  half  a  gram 
of  granulated  zinc  upon  it,  and  weigh  accurately.    The  difference 


326  APPENDIX 

between  this  weight  and  that  of  the  empty  glass  is  recorded  as  the 
exact  weight  of  the  zinc  used.  Thoroughly  clean  the  hydrogen 
generator,  and  raise  the  delivery-tube  in  the  stopper,  so  that  its 
end  is  flush  with  the  bottom  of  the  stopper.  With  the  aid  of  your 
wash-bottle  rinse  the  zinc  from  the  watch-glass  into  the  generator- 
bottle;  arrange  a  bottle,  as  usual,  in  the  pneumatic  trough;  but  set 
the  gas  generator  in  such  a  position  that  the  delivery-tube  is  not 
under  the  receiver.  Pour  one  drop  of  copper  sulphate  into  the 
funnel,  and  then  so  much  water  that  all  the  air  is  driven  out  of 
the  gas-generating  apparatus.  Now  push  the  end  of  the  delivery- 
tube  under  the  receiver,  and  pour  10-15  cc.  of  strong  hydrochlo- 
ric acid  down  the  funnel  tube,  cautiously  avoiding  the  carrying 
down  of  air  bubbles.  The  evolution  of  gas  will  begin  at  once; 
should  it  slacken  before  the  zinc  has  disappeared,  more  acid 
may  be  added.  (The  solution  of  the  zinc  takes  time,  and  the  suc- 
ceeding experiment  may  be  commenced  at  this  point.)  When  the 
zinc  has  all  been  dissolved,  pour  enough  water  down  the  funnel  to 
drive  all  remaining  gas  from  the  generator  into  the  receiver.  The 
volume  of  this  gas  is  now  measured  and  reduced  to  zero,  after 
ascertaining  its  actual  temperature  —  exactly  as  in  Experiment  14. 
A  cubic  centimeter  of  hydrogen,  at  zero,  weighs  approximately 
.00009  gram;  what  mass  of  hydrogen  was  evolved  in  this  experi- 
ment ?  How  many  parts  of  zinc  would  displace  one  part  of  hydro- 
gen from  its  combination  with  chlorine  ? 

EXP.  16.  Weigh  a  clean  and  dry  porcelain  dish  as  accurately 
as  possible,  add  about  two  grams  of  zinc  and  weigh  again.  Pour 
small  quantities  of  dilute  hydrochloric  acid  into  the  dish,  until  the 
zinc  is  all  dissolved;  profuse  addition  of  acid  would  result  in  loss 
of  time.  When  the  zinc  has  been  dissolved,  evaporate  carefully  to 
complete  dryness  on  the  evaporating  stove,  then  transfer  the  dish 
to  a  triangle  supported  on  a  ring-stand,  where  it  is  cautiously 
heated  until  the  zinc  chloride  has  just  melted,  the  burner  being 
held  in  the  hand,  and  the  flame  being  allowed  to  play  down  upon 
the  salt.  As  soon  as  the  latter  has  melted,  cool  without  delay.  As 
soon  as  the  dish  is  cool  enough  to  handle  without  burning  the 
fingers,  it  may  be  set  in  cold  water  —  of  course  without  moistening 
its  contents  —  so  as  to  reach  room  temperature  more  quickly.  Its 
outside  is  at  once  wiped  clean  and  dry  and  it  is  reweighed,  the 


APPENDIX  327 

gain  being  held  to  represent  the  chlorine  which  has  combined 
with  the  zinc.  How  much  chlorine  would  be  required  for  one  part 
of  zinc  ?  How  much  for  one  part  of  hydrogen  ? 

EXP.  17.  Brighten  a  piece  of  magnesium  ribbon,  and  weigh 
off  exactly  .04  grams  upon  a  watch-glass.  Place  the  magnesium 
in  a  beaker,  and  cover  it  with  a  small,  short-stemmed  funnel,  in- 
verted in  the  beaker.  Fill  the  latter  with  water.  Fill  a  eudiometer 
with  water,  cover  its  mouth  with  a  bit  of  bibulous  paper,  so  as  to 
be  able  to  invert  it,  and  set  it  so  that  its  rim  rests  on  the  funnel 
in  the  beaker,  with  the  stem  of  the  funnel  projecting  into  the  eudi- 
ometer. Remove  as  much  water  from  the  beaker  as  possible  without 
exposing  the  open  end  of  the  eudiometer,  and  pour  a  considerable 
amount  of  strong  hydrochloric  acid  into  the  beaker,  allowing  it  to 
run  down  the  walls,  so  as  to  form  a  layer  at  the  bottom.  It  will  soon 
work  its  way  to  the  magnesium,  which  will  quickly  dissolve,  the  dis- 
placed hydrogen  rising  into  the  measuring  tube.  When  the  reac- 
tion is  completed,  the  beaker  is  again  filled  brimful,  the  eudiometer 
slipped  off  the  funnel,  closed  with  the  thumb  and  transferred  to  a 
tall  cylinder  full  of  water,  where  it  is  allowed  to  remain  for  some 
time.  The  barometer  having  been  read,  and  the  temperature  of  the 
water  in  the  cylinder  having  been  noted,  the  eudiometer  is  lifted 
until  the  water  within  it  stands  at  the  same  level  as  that  without, 
and  the  volume  of  enclosed  hydrogen  is  read  off  on  the  engraved 
scale.  The  calculation  of  the  corresponding  mass  will  be  explained 
orally. 

EXP.  18.  Weigh  a  porcelain  crucible  and  lid,  after  cleaning 
and  drying  them.  Add  about  .8  gram  of  bright  magnesium  ribbon, 
and  weigh  again.  Set  the  crucible  on  a  pipestem  triangle,  on  a 
ring-stand,  and  heat  gradually  without  removing  the  lid,  except- 
ing for  a  moment  or  two  at  a  time  to  admit  fresh  air,  and  observe 
whether  the  magnesium  has  all  been  burned.  Avoid  the  escape  of 
a  white  smoke.  When  all  the  magnesium  appears  to  have  burned, 
remove  lid  and  heat  crucible  more  strongly.  Cool,  weigh  crucible 
with  lid  and  contents.  The  gain  in  weight  represents  oxygen.  In 
what  proportion  did  the  two  elements  combine  ? 

EXP.  19.  Charge  the  hydrogen-generator  with  some  zinc,  and 
replace  the  deli  very- tube  with  a  bent  tube  leading  to  a  U-tube  con- 


328  APPENDIX 

taining  a  little  strong  sulphuric  acid.  The  farther  end  of  the  U-tube 
communicates  with  a  hard-glass  tube,  by  means  of  a  connecting 
tube  and  stoppers.  While  the  hydrogen  is  sweeping  the  air  out  of 
the  generator  and  its  connections,  weigh  the  hard-glass  tube,  fill 
about  half -full  of  copper  oxide,  and  reweigh.  After  assuring  yourself 
that  the  air  has  been  driven  out  of  the  generator  according  to  Exp.  1, 
for  which  purpose  the  delivery-tube  may  be  temporarily  connected 
on,  put  the  copper  oxide  tube  in  position,  supporting  its  free  end 
with  the  aid  of  the  ring-stand.  Allow  a  minute  for  sweeping  the  air 
out  of  this  tube,  then  commence  to  warm  it  gradually  with  a  Bunsen 
flame.  Soon  steam  will  issue  at  the  jet,  and  care  must  be  taken  to 
keep  the  whole  tube  beyond  the  oxide  so  warm  that  water  may  not 
condense  and  run  back  to  crack  the  tube.  Whence  does  this  steam 
come  ?  Observe  what  happens  to  the  copper  oxide.  When  the 
change  is  complete,  allow  the  tube  to  cool  without  interrupting 
the  flow  of  hydrogen.  When  cold,  disconnect  and  reweigh.  With 
these  data,  calculate  the  ratio  in  which  copper  and  oxygen  combine. 

EXP.  20.  Weigh  a  porcelain  crucible  without  the  lid,  add  about 
1  gram  of  finely  divided  copper,  and  reweigh.  Fill  the  crucible 
about  a  quarter  full  of  nitric  acid,  cover  with  a  watch-glass,  convex 
side  down,  and  heat  very  gently  until  the  copper  is  dissolved;  lift 
off  the  watch-glass  and,  with  a  wash-bottle,  rinse  down  into  the 
crucible  the  green  drops  that  may  have  collected  on  it,  and  evapo- 
rate the  contents  of  the  crucible  to  dryness  on  the  stove.  When 
dry,  remove  with  forceps  to  pipe-stem  triangle,  and  heat  over  the 
free  flame,  cautiously  at  first,  but  more  strongly  toward  the  end, 
until  all  the  green  copper  nitrate  has  been  converted  into  black 
copper  oxide.  Cool  and  weigh.  The  gain  represents  the  oxygen 
which  is  now  combined  with  the  original  copper.  Compare  these 
two  weights  with  one  another. 

ALKALI  METALS 

EXP.  21.  Remove  the  kerosene  from  a  small  piece  of  sodium 
with  some  dry  filter-paper.  Drop  it,  in  small  bits,  into  water  con- 
tained in  a  porcelain  crucible,  keeping  a  lid  on  the  latter,  as  long  as 
chemical  action  is  taking  place.  When  the  sodium  has  disappeared, 
take  a  drop  of  the  solution  upon  the  end  of  a  glass  rod,  and  touch 
it  to  a  piece  of  red  litmus  paper;  then  add  hydrochloric  acid,  drop 


APPENDIX  329 

by  drop,  until  the  liquid  shows  an  acid  reaction.  Write  the  two 
equations  involved.  The  liquid  in  the  crucible  may  now  be  evapo- 
rated to  dryness,  and  the  product  examined. 

EXP.  22.  Counterpoise  a  beaker  upon  the  scales  and  add  25 
grams  of  a  "normal"  hydrochloric  acid,  —  one  gram  of  which 
contains  .0365  grams  of  HC1.  —  Warm  this  gently,  set  over  a  wire 
gauze.  Meanwhile,  place  something  more  than  two  grams  of  sodium 
carbonate  in  a  porcelain  dish,  and  weigh  (the  weight  of  the  empty 
dish  being  unimportant).  Carefully  transfer  this  salt,  a  little  at  a 
time,  to  the  acid,  by  means  of  a  horn  spatula,  until  the  liquid  is 
faintly  alkaline.  Reweigh  the  dish  to  find  the  amount  of  sodium 
carbonate  required  to  neutralize  the  acid. 

EXP.  23.  Repeat  experiment  22,  using  potassium  carbonate  in 
place  of  sodium  carbonate,  and  compare  the  two  results. 

EXP.  24.  Pour  100  cc.  of  calcium  hydroxide  into  a  clean  flask. 
Dissolve  a  quarter  of  a  gram  of  sodium  carbonate  in  half  a  test- 
tubeful  of  water,  and  add  just  enough  of  this  solution  to  the 
flask  to  complete  the  precipitation.  When  a  drop  produces  no 
further  precipitate,  add  a  few  drops  of  the  calcium  hydroxide; 
filter  and  neutralize  the  filtrate  with  hydrochloric  acid,  noticing 
whether  there  is  any  effervescence.  Pour  a  few  drops  of  acid  upon 
the  precipitate  on  the  filter  and  note  the  result. 

EXP.  25.  Weigh  a  clean  porcelain  crucible.  Add  one  gram  of 
potassium  chloride  and  reweigh.  Add  5  to  6  cc.  of  dilute  sulphuric 
acid.  Heat  gradually  in  fume-closet  until  dry;  allow  the  crucible 
to  cool,  and  moisten  the  contents  with  a  little  more  sulphuric  acid; 
evaporate  to  dryness.  Remove  crucible  to  pipe-stem  triangle 
supported  on  ring-stand  and  heat  with  Bunsen  burner,  but  not 
sufficiently  to  melt  the  salt.  Cool  and  weigh.  The  crucible  now  con- 
tains acid  potassium  sulphate,  KHSO4. 

EXP.  26.  Mix  on  a  piece  of  filter  paper  about  two  grams  of 
solid  ammonium  chloride  with  about  three  grams  of  powdered  cal- 
cium oxide.  Pour  the  mixture  into  a  specimen  tube  and  close  the 
latter  with  a  perforated  stopper,  through  which  passes  a  straight 
glass  tube.  Over  this  tube  slip  an  inverted  test-tube,  to  the  mouth 
of  which  a  piece  of  moistened  red  litmus  paper  has  been  made  to 


330  APPENDIX 

adhere.  Hold  the  specimen  tube  in  a  wire  support,  and  heat  the 
solid  mixture  gently;  ammonia  will  be  given  off,  as  can  be  recognized 
by  the  litmus  paper.  When  the  test-tube  appears  to  be  well  filled 
with  the  gas,  remove  it  from  the  generating  apparatus  and  hold  its 
open  end  under  the  surface  of  some  water  contained  in  a  beaker. 

EXP.  27.  Place  a  few  cubic  centimeters  of  ammonium  chloride 
solution  in  an  evaporating  dish,  add  4  to  5  drops  of  potassium  hy- 
droxide. Test  the  mixture  with  litmus  paper.  Now  warm,  holding 
pieces  of  moistened  red  litmus  paper  above  the  surface  of  the  liquid 
until  no  more  alkaline  gas  is  given  off.  Test  the  solution  with  red 
litmus  paper. 

EXP.  28.  Place  a  little  dry  ammonium  chloride  in  the  bottom  of 
a  dry  test-tube  and  warm  until  the  salt  has  volatilized.  It  will  be 
observed  to  condense  into  crystals  upon  the  cold  walls  of  the  test- 
tube.  This  is  called  "sublimation." 

CALCIUM  GROUP 

EXP.  29.  Weigh  a  clean  porcelain  crucible;  add  about  one  gram 
of  calcium  carbonate,  weigh  again.  Heat  on  pipe-stem  triangle 
gradually,  using  chimney  on  burner,  for  about  fifteen  minutes.  Cool, 
weigh.  The  loss  represents  carbon  dioxide.  Pour  some  water  on  the 
residue,  and  note  behavior.  Test  with  litmus  paper. 

EXP.  30.  Hah*  fill  a  test-tube  with  calcium  hydroxide  solution. 
Pass  in  carbon  dioxide  by  means  of  a  clean  glass  tube  until  the 
precipitate  which  has  first  formed  re-dissolves.  Write  two  equations 
to  express  what  has  taken  place.  The  solution  that  you  obtained  is 
to  be  divided  into  three  parts  and  used  in  the  three  succeeding 
experiments. 

EXP.  31.  To  one-third  of  the  above  solution  add  calcium  hy- 
droxide solution. 

EXP.  32.  Dilute"another  portion  to  ten  times  its  volume  with 
distilled  water,  in  a  flask.  Add  twenty  drops  of  soap  solution  and 
shake  vigorously. 

EXP.  33.  The  last  portion  is  to  be  boiled,  filtered  into  a  per- 
fectly clean  flask,  diluted  to  ten  times  its  volume  with  distilled 
water.  Add  twenty  drops  of  soap  solution,  and  shake  vigorously. 


APPENDIX  331 

EXP.  34.  Weigh  about  a  gram  of  gypsum  carefully  in  a  porce- 
lain crucible,  heat  strongly,  cool  and  reweigh.  Heat  a  second  time, 
to  see  whether  a  second  loss  of  weight  occurs.  This  loss  of  weight 
is  due  to  the  driving  off  of  water  of  crystallization.  How  much 
water  was  present  in  the  natural  gypsum  ?  Shake  the  residue  into 
a  watch-glass,  stir  up  with  a  few  drops  of  water,  and  observe  the 
result. 

EXP.  35.  Prepare  three  test-tubes  containing  calcium  chloride, 
strontium  chloride,  and  barium  chloride,  respectively,  each  diluted 
with  about  four  times  their  volume  of  water.  To  these  three  test 
tubes  add  equal  quantities  of  calcium  sulphate  solutions  (about  25 
drops  for  each).  Observe  and  discuss  results. 

ZINC,  CADMIUM,  AND  MAGNESIUM 

Hydrogen  sulphide,  which  is  used  in  this  exercise,  may  be  obtained  from  taps  in 
the  room  set  apart  for  the  purpose.  The  student  must  affix  his  own  glass 
tube  to  the  rubber  hose  set  on  these  taps.  As  the  number  of  outlets  is  limited, 
considerable  time  will  be  saved  if  the  students  will  prepare  the  solutions 
required  for  the  following  four  experiments  at  one  time,  and  carry  the  test 
tubes  on  a  rack  into  the  sulphuretted  hydrogen  room.  If  the  gas  is  passed  into 
the  test  tubes  in  the  prescribed  order,  the  glass  delivery  tube  need  not  be 
cleansed  between  the  experiments.  It  should  finally  be  cleaned  with  a  little 
strong  acid. 

EXP.  36.  Dilute  about  5  cc.  of  zinc  chloride  with  an  equal 
amount  of  water.  If  the  solution  is  acid,  neutralize  as  nearly  as 
possible  with  ammonium  hydroxide.  Treat  with  hydrogen  sulphide. 

EXP.  37.  Acidify  a  similar  solution  of  zinc  chloride  with  hydro- 
chloric acid  and  treat  with  hydrogen  sulphide. 

EXP.  38.  Dilute  about  5  cc.  of  cadmium  chloride  solution  to 
one-half  its  original  strength.  Acidify  with  hydrochloric  acid  and 
treat  with  hydrogen  sulphide. 

EXP.  39.  Mix  approximately  equal  volumes  of  the  solutions  of 
zinc  and  cadmium  chlorides.  Dilute  somewhat,  acidify  with  hydro- 
chloric acid  and  pass  hydrogen  sulphide  into  the  mixture  until  no 
more  precipitate  forms.  Separate  the  precipitate  from  the  solution 
by  filtration,  allowing  the  liquid  to  run  into  an  evaporating  dish. 
Set  the  latter  upon  the  evaporating  stove  in  your  fume  closet 
and  concentrate  to  dryness.  Meanwhile  wash  the  precipitate  once 


332  APPENDIX 

with  distilled  water.  Perforate  the  filter  with  a  sharpened  match- 
stick,  rinse  its  contents  into  a  test-tube  with  the  aid  of  a  wash 
bottle.  Allow  the  solid  to  settle  and  pour  off  as  much  as  possible 
of  the  water.  Add  5  cc.  of  hydrochloric  acid.  Warm  until  the 
precipitate  has  dissolved.  Boil  for  4  or  5  minutes.  Nearly  neutral- 
ize with  ammonium  hydroxide  and  add  ammonium  carbonate. 

The  concentrated  filtrate  is  poured  from  the  evaporating  dish  into 
a  test-tube,  diluted,  rendered  alkaline  with  ammonia  and  treated 
with  hydrogen  sulphide. 

EXP.  40.  To  a  solution  of  magnesium  sulphate  add  ammonium 
hydroxide  solution. 

EXP.  41.  To  5  cc.  of  magnesium  sulphate  solution  add  5  cc. 
of  ammonium  chloride  solution,  then  add  ammonium  hydroxide 
solution. 

EXP.  42.  To  the  solution  obtained  in  the  last  experiment,  add 
hydrogen  sodium  phosphate  solution. 

ALUMINUM 

EXP.  43.  Dilute  a  little  aluminum  sulphate  solution  and  add 
an  excess  of  ammonium  hydroxide  solution. 

EXP.  44.  Prepare,  in  separate  test-tubes,  very  dilute  solutions 
of  potassium  hydroxide  and  of  sulphuric  acid,  and  study  their  ac- 
tion upon  aluminum  sulphate,  as  follows :  — 

Dilute  10  cc.  of  the  aluminum  sulphate  solution  with  an  equal 
bulk  of  water  and  add  potassium  hydroxide,  drop  by  drop,  until  a 
precipitate,  which  forms  at  first,  disappears  upon  shaking  the  test- 
tube.  Divide  the  solution  into  equal  halves  (a)  and  (b).  Acidify 
portion  (a)  with  dilute  sulphuric  acid,  drop  by  drop,  until  the  pre- 
cipitate, which  forms  at  first,  again  disappears.  Reunite  portions 
(a)  and  (b) .  Write  five  equations  expressing  the  various  reactions 
that  have  taken  place. 

EXP.  45.  Mix,  upon  a  watch-glass,  concentrated  aluminum  sul- 
phate solution  with  concentrated  potassium  sulphate  solution. 

EXP.  46.  Throw  a  little  aluminum  foil  into  a  test-tube  con- 
taining some  strong  hydrochloric  acid. 


APPENDIX  333 

EXP.  47.  Throw  some  aluminum  foil  into  a  test  tube  containing 
some  strong  potassium  hydroxide  solution  and  warm  gently. 

EXP.  48.  Hang  two  strips  of  cotton,  one  of  which  has  been  soak- 
ing in  a  solution  of  aluminum  acetate,  over  a  glass  rod,  and  suspend 
them  in  a  solution  of  logwood  for  five  minutes.  Remove  them  to  a 
beaker  and  wash  with  plenty  of  water.  Observe  whether  the  dye 
adheres  more  firmly  to  one  sample  than  to  the  other. 

MERCURY 

NOTE.  As  mercury  and  its  compounds  corrode  lead  pipes,  the  slops  must  be 
thrown  into  jars  specially  provided,  and  not  into  the  sink. 

EXP.  49.  Place  about  5  cc.  of  mercurous  nitrate  solution  in  a 
test-tube,  and  dilute  with  an  equal  amount  of  water,  then  add 
potassium  hydroxide. 

EXP.  50.  Dilute  5  cc.  of  mercuric  nitrate  solution  with  an  equal 
quantity  of  water  and  add  potassium  hydroxide. 

EXP.  51.  Add  hydrochloric  acid  to  mercurous  nitrate  solution. 
EXP.  52.  Add  hydrochloric  acid  to  mercuric  nitrate  solution. 

EXP.  53.  Add  stannous  chloride  solution,  drop  by  drop,  to  a 
test-tube  half  filled  with  mercuric  chloride  solution. 

EXP.  54.  Allow  a  drop  of  mercurous  nitrate  to  remain  for  a  few 
moments  on  a  clean  copper  surface,  rinse  the  copper  in  a  little  water, 
wipe  dry  with  filter-paper,  then  heat  in  flame. 

TIN  AND  LEAD 

EXP.  55.  Allow  hydrogen  sulphide  gas  to  act  on  stannous 
chloride. 

EXP.  56.  Allow  hydrogen  sulphide  gas  to  act  on  stannic 
chloride. 

EXP.  57.  Drop  some  tinfoil  into  a  test-tube  with  hydrochloric 
acid  and  observe  effect  in  cold  and  heat. 

EXP.  58.  Place  tin-foil  in  a  crucible,  set  the  latter  inside  the 
fume-closet  and  add  strong  nitric  acid. 


334  APPENDIX 

EXP.  59.  Treat  some  litharge  (PbO)  with  dilute  nitric  acid 
until  dissolved.  Test  a  portion  of  the  solution  with  hydrochloric 
acid. 

EXP.  60.  Place  a  few  grams  of  "red  lead"  in  a  test-tube,  half 
fill  the  latter  with  cold  dilute  nitric  acid  and  shake.  Filter  the  solu- 
tion from  the  brown  residue,  and  test  the  former  with  a  few  drops  of 
hydrochloric  acid.  What  has  gone  into  solution?  What  is  the  brown 
residue ?  What  can  we  conclude  as  to  the  nature  of  "red  lead"  ? 

EXP.  61.  Add  hydrochloric  acid  to  10  cc.  of  lead  acetate  solu- 
tion, in  a  test-tube,  as  long  as  a  precipitate  continues  to  form.  Al- 
low the  latter  to  settle,  pour  off  the  clear  liquid,  shake  the  precipi- 
tate with  about  10  cc.  of  fresh  water,  allow  to  settle  and  pour  off 
water.  Repeat  this  washing  and  then  half  fill  the  test-tube  with 
water,  heat  to  boiling  and  filter,  if  necessary,  into  a  clean  test-tube. 
It  is  well  to  have  the  filter  ready  in  advance,  as  the  liquid  must  be 
filtered  boiling  hot.  Cool  the  clear  filtrate  by  running  water  over  the 
outside  of  the  test-tube. 

EXP.  62.  Precipitate  10  cc.  of  lead  acetate  with  potassium 
iodide  and  proceed  as  in  Exp.  61. 

CHROMIUM  AND  MANGANESE 

EXP.  63.  Render  chromium  sulphate  solution  alkaline  with 
potassium  hydroxide. 

EXP.  64.  Acidify  chromium  sulphate  solution,  and  note  whether 
hydrogen  sulphide  gas  affects  it. 

EXP.  65.  Acidify  some  potassium  chromate  solution,  pass  in 
hydrogen  sulphide  until  the  test-tube  smells  strongly  of  the  gas, 
filter  and  add  potassium  hydroxide  to  the  filtrate. 

EXP.  66.  Add  sulphuric  acid  to  15  cc.  of  potassium  chromate 
solution  in  a  dish  until  the  color  has  changed  completely.  Evapo- 
rate until  crystals  commence  to  form.  Then  set  aside  to  cool. 

EXP.  67.  Add  potassium  chromate  to  lead  acetate. 

EXP.  68.  Mix  a  little  manganese  dioxide  with  sodium  car- 
bonate powder  on  a  porcelain  crucible-lid.  Set  on  a  pipe-stem 
triangle  and  heat  until  the  mass  is  fused.  Cool,  set  in  a  beaker,  dis- 


APPENDIX  335 

solve  the  melt  in  water,  add  sulphuric  acid.   Note  any  changes 
of  color. 

EXP.  69.  Dilute  1  cc.  of  stannous  chloride  in  a  beaker  with 
25  cc.  of  water;  add  5  cc.  of  hydrochloric  acid.  Stir,  and  add 
potassium  permanganate  solution  drop  by  drop.  What  is  taking 
place  ? 

IRON 

EXP.  70.  Add  ammonium  hydroxide  to  ferrous  sulphate  solu- 
tion. 

EXP.  71.  Add  ammonium  hydroxide  to  ferric  chloride  solu- 
tion. 

EXP.  72.  Add  2  cc.  dilute  sulphuric  acid  to  5  cc.  of  ferrous 
sulphate  solution,  then  10  drops  of  nitric  acid,  and  heat.  Observe 
that  the  solution  becomes  almost  black  and  suddenly  clears,  giving 
off  red  fumes.  Add  a  couple  of  drops  of  nitric  acid  and  continue 
doing  this  until  no  more  red  fumes  appear.  Cool  and  render  alka- 
line with  ammonium  hydroxide. 

EXP.  73.  Add  some  hydrochloric  acid  and  a  little  metallic  iron 
to  10  cc.  of  ferric  chloride  solution.  As  soon  as  this  solution  has 
become  colorless,  filter  into  a  fresh  test-tube,  and  add  ammonium 
hydroxide. 

EXP.  74.  Add  stannous  chloride  to  ferric  chloride,  until  color- 
less, and  then  make  alkaline  with  potassium  hydroxide. 

EXP.  75.  Dilute  a  little  ferrous  sulphate  in  a  beaker  with 
water,  add  a  few  drops  of  sulphuric  acid,  and  then  potassium  per- 
manganate, drop  by  drop. 

EXP.  76.  Add  potassium  ferrocyanide  to  ferrous  sulphate. 

EXP.  77.  Add  potassium  ferrocyanide  to  ferric  chloride. 

EXP.  78.  Add  potassium  ferricyanide  to  ferrous  sulphate. 

EXP.  79.  Add  potassium  ferricyanide  to  ferric  chloride. 

EXP.  80.  Add  potassium  sulphocyanate  to  ferrous  sulphate. 

EXP.  81.  Add  potassium  sulphocyanate  to  ferric  chloride. 


336  APPENDIX 

COPPER 

EXP.  8£.  Test  the  action  of  hydrochloric,  nitric  and  hot  sul- 
phuric acids  on  copper,  noting  the  fumes  that  are  given  off  in  each 
case. 

f  EXP.  83.  Dilute  5  cc.  of  copper  sulphate  solution  with  an  equal 
quantity  of  water.  Add  small  bits  of  iron  and  heat.  What  changes 
take  place? 

!  EXP.  84.  Add  potassium  hydroxide  to  copper  sulphate  solu- 
tion until  it  is  strongly  alkaline. 

EXP.  85.  Add  ammonium  hydroxide  to  copper  sulphate  drop 
by  drop,  amid  constant  shaking,  until  the  solution  is  alkaline. 

1  EXP.  86.  Weigh  out  .4  gram  of  crystallized  copper  sulphate 
(which  contains  about  .1  gram  of  copper),  and  dissolve  in  9.6  cc. 
of  water.  Measure  1  cc.  of  this  solution  into  a  test-tube  and  mix 
with  9  cc.  of  water.  To  a  portion  of  this  diluted  solution  add  a  few 
drops  of  ammonium  hydroxide;  of  the  remainder,  measure  1  cc. 
into  a  fresh  test-tube  and  mix  with  9  cc.  of  water.  Test  a  portion  of 
this  more  dilute  mixture  with  ammonium  hydroxide,  and  proceed 
as  before,  always  preparing  a  solution  one-tenth  as  strong  as  the 
preceding  one,  until  a  drop  of  ammonium  hydroxide  fails  to  pro- 
duce a  noticeable  coloration.  Calculate  the  amount  of  copper  per 
cubic  centimeter  that  is  required  to  give  a  visible  reaction  with 
the  ammonium  hydroxide. 

EXP.  87.  Add  potassium  ferrocyanide  to  dilute  copper  sul- 
phate solution. 

EXP.  88.  Weigh  a  crucible;  add  about  two  grams  of  crystallized 
copper  sulphate;  weigh  again.  Heat  carefully  until  the  salt  is  quite 
white;  cool,  and  reweigh.  How  much  water  did  the  crystals  contain? 
Add  a  drop  of  water  to  the  white  residue. 

SILVER 

EXP.  89.  Add  hydrochloric  acid,  little  by  little,  to  5  cc.  of  sil- 
ver nitrate  until  no  more  precipitate  is  formed.  Throw  the  pre- 
cipitate upon  a  filter  and  wash.  Then  open  out  the  filter  and 


APPENDIX  337 

expose  the  precipitate  to  the  daylight  in  such  a  manner  that  a 
portion  is  covered  by  something  opaque.  Examine  from  time  to 
time. 

EXP.  90.  Add  enough  hydrochloric  acid  to  silver  nitrate  solu- 
tion to  effect  complete  precipitation.  Add  an  excess  of  ammonium 
hydroxide,  and  shake  vigorously.  Acidify  with  nitric  acid;  add 
more  ammonium  hydroxide. 

EXP.  91.  Add  hydrochloric  acid  to  5  cc.  of  silver  nitrate  solu- 
tion; allow  the  precipitate  to  settle;  pour  off  the  clear  liquid;  add 
water  to  wash  the  precipitate;  pour  off  the  wash- water.  Shake  the 
precipitate  with  a  solution  of  sodium  thiosulphate. 

EXP.  92.  Clean  a  test-tube  very  thoroughly  by  heating  nitric 
acid  in  it.  Pour  away  the  acid  and  introduce  5  cc.  of  silver  nitrate 
solution.  Add  ammonium  hydroxide  until  the  precipitate  which 
formed  at  first  is  redissolved.  Add  a  few  cc.  of  grape  sugar  solution 
and  warm  gently  until  the  silver  is  deposited.  Pour  the  liquid 
away,  and  examine  the  color  of  the  silver  by  transmitted  light. 

LABORATORY  MAXIMS 

There  is  no  such  phrase  as  "  clean  enough." 
Never  scrub  off  to-morrow  what  you  can  dissolve  to-day. 
Towels  are  used  for  drying,  not  for  rubbing  off  dirt. 

Neighbors'  eyes  were  not  meant  for  targets,  nor  their  noses  for 
fume-receptacles . 

Glass  and  porcelain  are  not  able  to  stand  sudden  changes  of 
temperature. 

Weights  and  hot  crucibles  should  not  be  held  in  the  fingers. 

Note-books  have  good  memories;  jottings  on  loose  paper  are 
useful  when  you  can  find  them. 

An  unrecorded  experiment  was  never  begun. 

Chemical  equations  explain  reactions,  but  do  not  describe  them. 

Too  much  of  a  reagent  is  as  bad  as  too  little;  and  the  latter 
fault  can  be  remedied. 

Repairing  damages  takes  much  longer  than  avoiding  them. 


338  APPENDIX 

The  following  series  of  lecture  experiments,  taken  from  the  notes  of  one  of  Pro- 
fessor Loeb's  lectures  on  physical  chemistry,  may  find  a  fitting  place  here,  at  the 
close  of  the  elementary  experiments.  The  outcome  illustrates  the  point  of  view  taken 
by  the  first  paper  (pages  1  to  20)  of  this  volume.  [EDITOR.! 

I  DESIRE  to  show  you  a  series  of  experiments  devised  by  Pro- 
fessor Landolt,  of  Berlin,  illustrating  a  class  of  phenomena  that 
are  grouped  together  under  the  name  of  Speeds  of  Reaction.  In 
this  particular  case  we  shall  examine  the  rapidity  with  which  a  re- 
action takes  place  between  iodic  acid  and  sulphurous  acid.  In  the 
first  place,  the  sulphurous  acid  serves  to  reduce  the  iodic  acid  to 
hydriodic  acid,  which  as  soon  as  the  sulphurous  acid  is  exhausted 
will  react  with  any  remnant  of  the  iodic  acid,  producing  water  and 
free  iodine.  Up  to  the  moment  that  the  last  particle  of  sulphurous 
acid  has  disappeared,  or  rather,  been  converted  into  sulphuric  acid, 
it  is  impossible  that  iodine  should  be  separated  in  the  free  state; 
consequently  the  appearance  of  this  free  iodine  will  be  an  indication 
of  the  time  it  takes  for  the  completion  of  the  reaction  between  the 
original  substances.  If  this  reaction  were  instantaneous,  the  ap- 
pearance of  iodine  would  immediately  follow  the  mixing  of  the  two 
solutions;  but  you  will  soon  see  that  this  is  not  the  case.  Time  is 
necessary  for  the  molecular  exchange,  and  in  this  case,  the  interval 
is  sufficiently  great  to  be  readily  measured  by  means  of  an  ordinary 
watch. 

In  order  to  enable  you  to  detect  the  iodine  the  moment  it  is  set 
free,  I  shall  mix  with  the  solution  a  little  starch  paste,  which,  as 
you  well  know,  gives  a  blue  color  with  free  iodine.  Perhaps,  how- 
ever, I  had  better  show  you  this  in  the  first  place.  I  take  here  some 
starch  paste  in  three  beakers;  to  the  first  I  add  some  iodic  acid, 
to  the  second  some  hydriodic  acid  and  to  the  third  a  solution  con- 
taining a  little  free  iodine.  You  see  that  only  the  third  beaker  shows 
a  decided  blue  color;  iodine  in  combination  not  affecting  the  starch 
in  this  way. 

We  are  now  ready  to  begin  with  the  experiment  on  speed 
of  reaction.  In  the  first  place,  I  measure  out  25  cc.  of  iodic 
acid  solution  in  one  beaker  and  25  cc.  of  sulphuric  acid  into 
another.  The  iodic  acid  solution  being  slightly  stronger,  we  shall 
have  a  little  excess  of  this  reagent,  to  which  I  add  5  cc.  of  starch 
paste  solution  and  20  cc.  of  water.  I  shall  now  mix  the  two  solu- 


APPENDIX  339 

tions  rapidly  and  note  the  time  which  elapses  until  the  blue  color 
sets  in. 

The  experiment  is  now  to  be  repeated;  but  I  take  solutions  which 
have  been  warmed  in  order  that  the  molecules  may  move  more 
rapidly.  The  relative  quantities  of  the  total  volume  remain  the 
same.  You  note  how  much  more  rapidly  the  molecular  exchange  has 
taken  place. 

In  order  now  to  show  you  that  space  has  something  to  do  with 
this  reaction,  I  must  increase  the  distances  between  the  molecules  in 
order  that  they  shall  be  obliged  to  traverse  more  than  the  previous 
distance  in  order  that  they  may  meet  one  another.  How  can  I  do 
this  ?  Simply  by  distributing  them  evenly  over  a  larger  amount 
of  water.  You  will  remember  that  I  had  employed  25  cc.  of  each 
acid  solution,  5  cc.  of  starch  paste  and  20  cc.  of  water,  or  75  cc. 
in  all.  If  I  now  preserve  all  of  these  measures,  excepting  that  I 
substitute  95  cc.  of  water  for  the  20,  the  total  bulk  will  be  150 
cc.,  while  the  molecules  of  reacting  acids  will  remain  the  same.  In 
this  case,  then,  the  speed  is  very  much  diminished,  although  the 
time  required  is  not  exactly  doubled,  for  there  are  so  many  other 
questions  entering  in  here,  —  the  reaction  is  complicated. 

In  order  to  produce  still  another  effect,  I  shall  maintain  the  quan- 
tities of  this  last  experiment,  but  raise  the  temperature.  The  time 
now  approximates  that  of  the  first  experiment. 

Yet  another  variation  may  be  easily  made;  I  shall  increase  the 
amount  of  iodic  acid  while  maintaining  the  amount  of  sulphurous 
acid,  and  I  shall  again  so  arrange  that  the  total  volume  is  75  cc. 
A  little  explanation  is  here  necessary,  inasmuch  as  I  shall  take 
only  25  cc.  of  iodic  acid  solution,  but  this  is  made  of  just  double 
the  strength  of  the  one  I  originally  used.  In  this  case,  again,  you 
will  see  the  speed  of  reaction  is  augmented  and  the  time  very  much 
reduced. 

The  results  that  I  have  shown  you  here  involve  energy,  space,  and 
time,  as  well  as  matter,  and  I  have  varied  the  energy  by  changing 
the  temperature,  and  the  space  by  changing  the  volume,  and  you 
have  seen  how  time  was  affected. 


BIBLIOGRAPHY  OF  MORRIS  LOEB 


Title 

Journal 

Vol. 

Pages 

Year 

Page 
of  this 
Vol. 

1 

Ueber  die  Einwirkung 

Ber.  d.  deutsch. 

18 

2427-28 

1885 

169 

von  Phosgen  auf  Ae- 

ch.  Gesch. 

thenyldiphenyldiamin 

2 

Ueber  Amidinderivate 

Ber.  d.ch.Ges. 

19 

2340-44 

1886 

171 

3 

Das  Phosgen  und  seine 

Thesis      Uni- 

1887 

177 

Abkoemmlinge  nebst 

vers.  of  Ber- 

einigen Beitraegen  zu 

lin,    March, 

deren  Kenntnis 

1887 

4 

Das  Phosgen  und  seine 

Chem.  Cen- 

18/1 

635-37 

1887 

Abkoemmlinge  nebst 

tralbl.(3) 

einigen  Beitraegen  zu 

deren  Kenntnis 

5 

Molecular  Weight  of  Io- 

J. Chem.  Soc. 

53 

805-12 

1888 

230 

dine  in  its  Solutions 

6 

Ueber   den   Molekular- 

Z.   Physik. 

2 

606-12 

1888 

239 

zustand  des  geloesten 

Chem. 

lods 

7 

Use  of  Aniline  as  an  Ab- 

J. Chem.  Soc. 

53 

812-14 

1888 

248 

sorbent  of  Cyanogen 

in  Gas  Analysis 

8 

Zur     Kinetik     der     in 

Z.    Physik. 

2 

948-63 

1888 

251 

Loesung  befindlichen 

Chem. 

Koerper     (with    W. 

Nernst) 

9 

The  Rates  of  Transfer- 

Am. Chem.  J. 

11 

106-21 

1889 

273 

ence  and  the  Conduct- 

ing Power  of  Certain 

Silver  Salts  (with  W. 

Nernst) 

10 

The  Use  of  the  Gooch 

J.  Am.  Chem. 

12 

300-01 

1890 

293 

Crucible  as  a  Silver 

Soc. 

Voltameter 

11 

Osmotic    Pressure   and 

Am.  Chem.  J. 

12 

130-35 

1890 

21 

the  Determination  of 

12 

Molecular  Weights 
The    Electrolytic    Dis- 

Am. Chem.  J. 

12 

506-16 

1890 

30 

sociation  -  Hypothesis 

of  Svante  Arrhenius 

13 

Review    of    Ostwald's 

Am.  Chem.  J. 

12 

516 

1890 

45 

Grundriss  der  Allge- 

meinen  Chemie 

14 

Is  Chemical  Action  Af- 

Am. Chem.  J. 

13 

145-53 

1891 

295 

15 

fected  by  Magnetism  ? 
Apparatus  for  the  De- 

J. Am.  Chem. 

13 

263-64 

1891 

306 

lineation    of    Curved 

Soc.;   also 

Surfaces  in   Illustra- 

Chem. News 

65 

220-21 

1892 

tion  of  Gases,  etc. 

APPENDIX 


341 


Title 

Journal 

Vol. 

Pages 

Year 

Page 
of  this 
Vol. 

16 

Laboratory  Manual  Pre- 

New York 

— 

1-20 

1900 

321 

pared  for  Students  in 

Elementary  Inorganic 

Chemistry    at     New 

York  University 

17 

The  Province  of  a  great 

Science 

16 

485-86 

1902 

46 

Endowment    for  Re- 

search 

18 

Crystallization  of  Sodi- 

J. Am.  Chem. 

27 

1019-20 

1905 

308 

um  Iodide  from  Alco- 

Soc. 

hols 

19 

The  Vapor  Friction  of 

Science 

21 

818-819 

1905 

310 

Isomeric  Ethers  (with 

F.  S.  M.  Peterson) 

20 

Hypothesis  of  Radiant 
Matter 

Pop.    Science 
Monthly 

73 

52-60 

1908 

64 

21 

Report  of  the  Commit- 

Reports    of 

— 

1159-70 

1909 

78 

tee  to  Visit  the  Chemi- 

Committees 

.    cal  Laboratory  of  Har- 

of  Harvard 

'  vard  College  (with  J. 

Overseers 

Collins  Warren,  Clif- 

ford Richardson,  and 

James  M.  Crafts) 

22 

Conditions       Affecting 

Science 

30 

664-68 

1909 

93 

Chemistry     in    New 

York 

23 

Abstractor  (Italian)    for 

J.  Amer. 

— 



1908-10 

Chemical  Abstracts 

Chem.  Soc. 

24 

Analysis  of  Some  Boliv- 

J. Amer. 

32 

652-53 

1910 

312 

ian  Bronzes  (with  S. 

Chem.  Soc. 

R.  Morey) 

25 

Oliver  Wolcott  Gibbs 

Proc.     Amer. 

— 

69-75 

1910 

108 

Chem.  Soc. 

26 

The     Chemists'    Club, 

The  Chemists' 



15-17 

1910-11 

118 

New  York 

Club     Year 

Book 

27 

The  Chemists'  Building 

J.    Ind.   Eng. 

3 

205-08 

1911 

121 

Chem. 

28 

Address  at  Opening  of 

Met.  and 

9 

177-78 

1911 

128 

Chemists'  Building 

Chem.  Eng. 

29 

The     Eighth     Interna- 

J.   Ind.   Eng. 

4 

556-57 

1912 

152 

tional  Congress  of  Ap- 

Chem. 

plied  Chemistry 

30 

Coal    Tar    Colors,    pp. 

1912  New 

5 

7^77 

1912 

132 

74-77 

Internat. 

31 

Periodic  Law,  pp.  593- 

Encyc. 
1912  New 

15 

593-97 

1912 

143 

597 

Internat. 

Encyc. 

32 

Studies  in  the  Speed  of 

Proc.  8th  Int. 

26 

601-04 

1912 

314 

Reductions 

Cong.  App. 

Chem. 

342 


APPENDIX 


Title 

Journal 

Vol. 

Pages 

Year 

Page 
of  this 

Vol. 

33 

The  Fundamental  Ideas 

This  volume 

~ 

1913 

3 

of  Chemistry  (Edited 

by  T.  W.  R.) 

34 

Atoms    and    Molecules 

This  volume 

— 



1913 

50 

(Edited  by  T.  W.  R.) 

35 

Sir  Isaac  Newton(Edited 

This  volume 

— 

— 

1913 

101 

byT.  W.  R.) 

36 

Chemistry  and  Civiliza- 

This volume 

— 

— 

1913 

156 

tion  (Edited  by  T.  W. 

R.) 

INDEX  OF  NAMES 


INDEX  OF  NAMES 


Accademia  del  Lincei,  153. 

Ador,  190,  205. 

Albertus  Magnus,  162. 

American  Academy  of  Arts  and  Sci- 
ences, 115. 

American  Association  for  the  Advance- 
ment of  Science,  122,  153. 

American  Chemical  Society,  xxiii,  94, 
98,  117,  119,  121,  122,  123,  125,  153. 

American  Electrochemical  Society,  98, 
121. 

American  Journal  of  Science,  111. 

American  Museum  of  Natural  History, 
312. 

Anne,  Queen,  103. 

Aristotle,  52. 

Arkwright,  162. 

Armstrong,  Henry  Edward,  40,  41,  42, 
43,  71,  205. 

Arrhenius,  Svante  August,  30, 31, 36, 37, 
39,  41,  42,  43,  44,  71,  251,  252,  265, 
271,  285,  286,  291,  340. 

Auwers,  K.,  229. 

Avogadro  di  Quaregna,  Amedeo,  24. 

Badische  Anilin  und  Soda  Fabrik,  88. 

Baeyer,  Adolph  von,  136,  139. 

Basarow,  203,  208. 

Baskerville,  Charles,  vii. 

Bauer,  184. 

Baxter,  Gregory  Paul,  vii,  78. 

Becher,  162. 

Beckmann,  Ernst,  28. 

Becquerel,  Jean,  66. 

Behla,  190,  206. 

Belar,  151. 

Bell,  295,  296. 

Benedikt,  142. 

Bergman,  162. 

Berju,  207. 

Berlin,  University  of,  88,  89,  228. 

Bernthsen,  220. 

Berthelot,  Marcellin,  183,  188,  205. 

Berthollet,  Claude  Louis,  8. 


Berolzheimer,  Daniel  D.,  vii. 

Berzelius,  Jons  Jacob,  8,  113,  181,  205. 

Birnbaum,  192,  206. 

Black,  Joseph,  177. 

Bladin,  J.  A.,  175. 

Bonhofer,  200. 

Bogert,  Marston  T.,  xxii. 

Bonty,  41,  42,  43. 

Bouchardat,  F.,  179,  198,  207. 

Bowman,  W.,  229. 

Boyle,  Robert,  24,  162. 

Boylstcn  Hall,  78,  79  et  seq. 

Bredig,  Georg,  24,  27. 

Buchka,  208. 

Bunsen,  Robert  Wilhelm,  106,  120. 

Butlerow,  189,  205. 

Cahours,  182,  205. 

Cannizzaro,  Stanislao,  6. 

Carius,  221. 

Carnegie  Institution  of  Washington,  46, 
48,  49. 

Carnot,  Sadi,  24. 

Carstanjen,  184. 

Cavendish,  154. 

Cazeneuve,  141. 

Century  Club,  110. 

Chandler,  Charles  F.,  xxii,  94. 

Chandler  Hall,  119,  125. 

Chaucourtois,  de,  144. 

Chemical  Laboratory  of  Harvard  Col- 
lege, xviii,  78,  112. 

Chemical  Museum,  126. 

Chemical  Society  of  London,  112. 

Chemische  Reichsanstalt,  100. 

Chemists'  Building,  121-127,  128,  341. 

Chemists'  Building  Company,  xviii,  118, 
126,  128. 

Chemists'  Club,  The,  vii,  xviii,  xxi,  xxii, 
94,  118-120,  121,  123,  125,  128,  131, 
341. 

Ciamician,  195,  206. 

Clark,  258,  262,  278,  279. 

Clark  University,  v,  vi,  xvii. 


346 


INDEX 


Clarke,  Frank  Wigglesworth,  113. 

Claudet,  112. 

Claus,  Carl  Ernst,  116. 

Clausius,  Rudolf,  30,  229,  252. 

College  of  the  City  of  New  York,  112, 119. 

College  of  Physicians  and  Surgeons,  111, 
112. 

Collin,  142. 

Columbia  Grammar  School,  111. 

Columbia  University,  94,  111,  119. 

Columbian  Exhibition,  152. 

Congress  of  Applied  Chemistry,  Eighth 
International,  xix,  xxi,  124,  152-154, 
341. 

Congress  of  Applied  Chemistry,  Seventh 
International,  93. 

Congress  of  Applied  Chemistry,  Trien- 
nial, 123. 

Conrad,  189,  208. 

Cooke,  Josiah  Parsons,  112. 

Cooper,  James  Fenimore,  110. 

Copernicus,  Nikolaus,  103. 

Cornell  University,  119. 

Couper,  R.  A.,  6. 

Cowardins,  184. 

Crafts,  James  M.,  92, 190, 192, 199,  200, 
205,  341. 

Cranston,  181,  205. 

Crichton,  The  Admirable,  3. 

Crompton,  41,  42. 

Crookes,  Sir  William,  67,  72,  146,  312. 

Daguerre,  157. 

Dalton,  John,  8,  53,  143. 

Dane  Hall,  78  et  seq. 

Davy,  Sir  Humphry,  177,  180,  205. 

Davy,  John,  178,  207. 

Davy-Faraday  Laboratories,  128. 

De  Clermont,  188,  205. 

Delaware  College,  112. 

Democritus,  53. 

Descartes,  Rene,  102. 

Deville,  St.  Claire  Henri,  5, 116. 

Dewar,  Sir  James,  19,  181,  205. 

Dittler,  196,  208. 

Doebereiner,  144. 

Donders,  25. 

Doremus,  Ogden,  94. 

Dumas,  Jean  Baptiste,  6,  112,  179,  180, 

192,  206. 
Dupertius,  207. 


Eastman  Kodak  Company,  90. 
Eckenroth,  188,  206. 
Edison,  Thomas  A.,  157. 
Elbs,  205. 

Emmerling,  181,  183,  184,  205. 
Escherich,  207. 
Ettingshausen,  von,  258. 

Falck,  196,  208. 

Faraday,  Michael,  8,  42,  48,  70,  87,  297. 

Fenton,  179,  207. 

Fischer,  Emil,  88. 

Fontaine,  188,  205. 

Forbes,  George  Shannon,  vii. 

Fossati,  296. 

Francksen,  207. 

Frankfort-on-Main,  Physical  Associa- 
tion of,  249. 

Franklin,  295,  297. 

Fraunhofer,  106. 

Free  Academy  of  New  York  City,  112. 

Fremy,  Edmonde,  115,  116. 

Friedel,  Charles,  187,  190,  192, 199,  200, 
205,  206. 

Friedlander,  142. 

Gabriel,  229. 

Galileo,  101,  103,  104,  105. 

Gallenberg,  Miss  Betty.  See  Mrs.  Solo- 
mon Loeb. 

Gattermann,  Ludwig,  206,  208. 

Gay-Lussac,  Josephe  Louis,  8,  24,  254, 
275. 

Geber,  162. 

General  Electric  Company,  88,  90. 

Genth,  F.  A.,  115,  116. 

Gerhardt,  Charles  Frederic,  6. 

German  Emperor,  88. 

Gibbs,  George,  111. 

Gibbs,  Josiah  Willard,  111. 

Gibbs,  Laura,  111. 

Gibbs,  Wolcott,  xvi,  xvii,  78,  108-117, 
120,  341. 

Gibbs  (Wolcott)  Memorial  Laboratory, 
xvii,  xix,  92. 

Girard,  Ch.,  132,  193,  207. 

Glauber,  162. 

Gmelin,  Leopold,  115. 

Goebel,  205. 

Goldstein,  Eugen,  66. 

Gooch,  F.  A.,  211,  293,  340. 


INDEX 


347 


Gradmann,  207. 
Graebe,  132,  190,  206. 
Green,  142. 

Griess,  P.,  132,  175,  224. 
Gronvik,  228. 
Guldberg,  36. 
Gustavson,  181,  205. 
Guthzeit,  189,  208. 

Hall,  94. 

Hallmann,  201,  208. 
Hamburger,  H.  J.,  25,  33. 
Hare,  H.  A.,  115. 

Harnitz-Harnitzky,  187,  188,  205,  206. 
Harvard  College,  xvi,  110,  341. 
Harvard  University,  xv,  xvi,  xvii,  xviii, 

xix,  xxiii,  78  et  seq.,  119. 
Havemeyer  Laboratory,  iii,  94. 
Heintz,  206. 
Hencke,  208. 

Henderson,  Lawrence  J.,  78. 
Hendrick,  Ellwood,  xxi. 
Henry,  205. 
Henry,  J.,  24,  157. 
Hentschel,  187,  197,  208. 
Herschel,  Sir  William,  51. 
Hertz,  87,  157. 
Hill,  A.  E.,  313. 
Hittorf,  251,  253,  260,  264,  268,  272, 

273,  274,  281,  285,  288,  292. 
Hoff,  J.  H.  van't,  22,  23,  24,  25,  28,  36, 

43,  48,  230,  239. 
Hofmann,  August  W.  von,  xvi,  5,  6, 109, 

120,  127,  132,  169,  174,  179,  181,  193, 

194,  195,  197,  204,  205,  207,  210,  217, 

220,  222,  225,  228,  248. 
Hofmann-Haus,  128. 
Hood,  J.  J.,  299,  301,  302. 
Horsford,  Eben,  5,  112. 
Hurst,  142. 
Huth,  151. 

Jackson,  Charles  Loring,  vii,  xvi,  78. 
Japan,  Imperial  University  of,  120. 
Jaquemin,  248. 

Johns  Hopkins  University,  119. 
Julius,  142. 

Kaufmann,  Walter,  65,  69. 
Kekule,  August,  6,  187,  188,  206. 
Keller,  204,  207,  209. 


Kempf,  187,  192,  205,  207. 

Kepler,  Johann,  103. 

Kirchhoff,  G.,  107. 

Kirmis,  253,  274. 

Knecht,  142. 

Kohler,  Elmer  P.,  vii. 

Kohlrausch,  Friedrich,  32,  43,  251,  252, 

253,  258,  264,  265,  267,  268,  269,  285, 

286,  287,  288,  289. 
Kolbe,  Hermann,  182,  205. 
Kraut,  187,  206. 

Kuhn,  Miss  Eda.  See  Mrs.  Morris  Loeb. 
Kuhn,  Loeb  and  Company,  xvi. 
Kuschel,  253,  274. 

Landolt,  Hans,  338. 

Larmor,  Sir  Joseph,  67. 

Laurent,  Auguste,  6,  112. 

Lauth,  132. 

Lavoisier,  162,  163. 

Lawrence  Scientific  School,  110,  112. 

Leblanc,  Nicolas,  83,  163. 

Le  Bon,  Gustav,  77. 

Le  Chatelier,  Henri  Louis,  111. 

Leclanche,  258,  279. 

Lefevre,  142. 

Leibnitz,  103. 

Leipzig,  University  of,  89,  230. 

Lellmann,  200. 

Lenard,  Philipp,  66. 

Lengyel,  181,  183,  205. 

Lenz,  253,  274. 

Lepsius,  249. 

Leuckart,  198,  200. 

Leverrier,  Urbain  Jean  Joseph,  105. 

Liebermann,  132,  190,  204,  206. 

Liebig,  Justus,  5,  6,  84. 

Lincoln,  Abraham,  122. 

Lippmann,  35. 

Lodge,  Sir  Oliver  J.,  40,  43. 

Loeb,  James,  xvii,  xix,  92. 

Loeb,  Morris,  bequests,  xxii,  xxiii,  99; 
Berlin  University,  work  at,  xvi,  xx, 
167-229;  bibliography,  340-342;  birth, 
xv  ;  character,  v,  xv-xxiii  ;  charities, 
xviii;  Chemists'  Building,  share  in, 
118;  Chemists'  Club,  presidency  of, 
xvii,  xxi;  Clark  University,  docent- 
ship  at,  xvii;  death,  xxi;  Detur,  xvi; 
Doctor  of  Philosophy,  xvi,  229;  edu- 
cation, xvi;  elementary  manual,  321- 


348 


INDEX 


339;  Harvard  College,  life  at,  xvi; 
Harvard  University,  Overseers  Com- 
mittee of,  xviii,  78-92;  Heidelberg  Uni- 
versity, work  at,  xvi,  xx;  honorable 
mention,  xvi;  honorary  degree,  xx; 
Leipzig  University,  work  at,  xvi,  xx, 
230-247;  marriage,  xxi;  membership 
in  societies,  xix;  memorial  laboratory 
in  honor  of,  120;  music,  interest  in, 
xx ;  New  York  University,  professor- 
ship at,  xvii;  researches,  v,  vi,  vii,  xx, 
167-317;  resolutions  in  appreciation 
of,  xxi,  xxii;  Sea  Bright,  country  house 
at,  xx.  See  also  259,  273,  338. 

Loeb,  Mrs.  Morris  (Eda  Kuhn),  xxi. 

Loeb,  Solomon,  xv,  xviii. 

Loeb,  Mrs.  Solomon  [Betty  Gallen- 
berg],  xv,  xviii,  xx. 

Lowenberg,  206. 

Lorentz,  Hendrik  Anton,  64. 

Louis  XVI,  161. 

Lowell,  James  Russell,  109. 

Lucasian  Professor  of  Mathematics,  102. 

Lurie,  192,  206. 

Magnaghi,  195,  206. 

Marcet,  181. 

Marconi,  Guglielmo,  157. 

Marignac,  Jean-Charles  Galissard  de,  116. 

Mars,  54. 

Massachusetts  Institute  of  Technology, 

119. 

Mauran,  Josephine,  112. 
Maxwell,  J.  Clerk,  64,  87. 
Medlock,  206. 
Mendeleeff,  Dmitri,  14,  41,  42,  43,  144, 

149,  151. 

Meyer,  Lothar,  14,  144,  311. 
Meyer,  Victor,  207. 
Meyerhoffer,  299. 
Michaelis,  A.,  196,  208. 
Michelson,  A.  A.,  299. 
Michigan,  University  of,  119. 
Michler,  W.,  193, 194, 198,  200, 204, 207, 

209,  217. 

Mirandola,  Pico  della,  3. 
Mond,  Ludwig,  48,  128. 
Morey,  S.  R.,  312,  341. 
Miihlhauser,  207. 
Murray,  John,  177,  178. 
Mylius,  E.,  206. 


Nasini,  238,  247. 

Natanson,  S.,  179,  207. 

National  Academy  of  Science,  110. 

Nemirowsky,  191,  206. 

Neptune,  51,  105. 

Nernst,  Walther,  xvi,  34,  35,  38,  40,  43, 

44,  251,  253,  264,  270,  273,  275,  291, 

340. 

Newlands,  J.,  14, 144,  151. 
Newton,  Hannah  Ayscough,  101. 
Newton,  Sir  Isaac,  vi,  101-107,  341. 
New  York  Academy  of  Sciences,  97. 
New  York,  College  of  City  of,  112,  119. 
New  York  University,  vii,  xvii,  94, 321, 

341. 

Nichols,  295,  297. 
Nichols,  William  H.,  xxii. 
Nietzki,  142. 
Noyes,  Arthur  A.,  315,  316. 

Olberg,  205. 

Olympian  games,  154. 

Ostwald,  Wilhelm,  xvi,  27,  33,  36, 40, 41, 
42,  43,  44,  45,  230,  239,  247,  252,  255, 
265,  266,  277,  286,  287,  340. 

Pahl,  207. 

Paracelsus,  162. 

Parthenon,  69. 

Pasteur,  Louis,  84. 

Paterno,  181,  205,  238,  247. 

Peligot,  206. 

Pennsylvania,  University  of,  115. 

Pennsylvania  Railroad,  90. 

Peterson,  F.  S.  M.,  310,  341. 

Pfeffer,  22,  25. 

Pickering,  S.  U.,  41,  42,  43,  44. 

Planck,  Max,  27,  40,  43,  235,  244. 

Poiseulle,  311. 

Pope,  Alexander,  107. 

Priestley,  154. 

Princeton  University,  119. 

Proust,  143. 

Prout,  67,  143,  144. 

Pupin,  Michael  Idvorsky,  23,  24. 

Rammelsberg,  Carl  Friedrich,  112. 
Ramsay,  Sir  William,  74,  75. 
Raoult,  F.  M.,  21,  22,  25,  26,  27,  230, 
231,  235,  238,  239,  240,  243,  246,  247. 
Rayleigh,  Lord  (J.  W.  Strutt),  48,  258. 


INDEX 


349 


Regnault,  Victor,   112,   178,   179,  180, 

207,  231,  234. 
Reicher,  44. 
Reichert,  E.  T.,  115. 
Reissert,  A.,  229. 
Remsen,  Ira,  295,  296. 
Richards,  Theodore  William,  78. 
Richardson,  142. 

Richardson,  Clifford,  xxi,  92,  341. 
Richter,  Jeremiah  Benjamin,  143. 
Righi,  Augusto,  65,  66. 
Rilliet,  205. 
Roemer,  206. 
Rontgen,  Wilhelm,  103. 
Roese,  185. 
Rose,  Heinrich,  112. 
Rosse,  Lord,  106. 
Rowland,  295,  296. 
Rowley,  Walter  E.,  xxi. 
Royal  Institution,  47. 
Royal  Society,  102,  152,  154. 
Ruhmkorff,  299. 
Rumford  Medal,  111. 
Rumford  professorship,  112. 
Runge,  132. 
Rutherford,  Ernest,  66,  72,  75,  76. 

Salomon,  193,  206. 

Sanger,  Charles  Robert,  78,  86. 

Sarauw,  207. 

Schiller,  108. 

Schmidt,  201,  208. 

Schone,  193,  206. 

Schreiner,  185. 

Schutzenberger,  181,  182,  205. 

Schultz,  141,  142. 

Seyewetz,  142. 

Siemens,  Werner,  127. 

Sisley,  142, 

Smithsonian  Institution,  99,  115. 

Snape,  208. 

Society  of  Chemical  Industry,  96, 98, 121. 

Solvay,  83. 

Soxhlet,  V.  H.,  28. 

Stacewitz,  187,  206. 

Stojentin,  209. 

Strassburg,  University  of,  88,  89. 

Thomsen,  Julius,  205. 
Thomson,  Sir  Joseph  John,  65,  68,  69, 
70,  77. 


Torrey,  Henry  Augustus,  78. 

Torricelli,  231. 

Trinity  College,  Cambridge,  102. 

Union  League  Club,  110. 
United  States  Sanitary  Commission,  110. 
United  States  Steel  Corporation,  87. 
United  States  Treasury  Department,  130. 

Venable,  F.  P.,  151. 

Verein  zur  Hebung  der  chemischen  In- 
dustrie, 127. 
Villon,  141. 

Virginia,  University  of,  119. 
Volhard,  J.,  254,  275,  308. 
Vries,  Hugo  de,  25,  33,  43,  44. 

Waage,  36. 
Walker,  James,  27. 
Warren,  J.  Collins,  92,  341. 
Wartmann,  E.,  295. 
Watt,  James,  162. 
Weiske,  253,  274. 
Werner,  A.,  116. 
Westminster  Abbey,  101,  103. 
Wharton,  Joseph,  109. 
Wiedemann,  E.,  40,  41,  43,  239,  298. 
Wiedemann,  G.,  253,  258,  274. 
Wiley,  Harvey  Washington,  28. 
Wilhelm  II,  German  Emperor,  88. 
Will,  W.,  27,  203,  204,  208. 
Williamson,  Alexander  W.,  6,  30,  252, 

308. 

Willm,  E.,  116,  193,  205,  207,  208. 
Wischin,  205,  208. 
Wohler,  Friedrich,  6. 
Wolcott,  Oliver,  111. 
Wollaston,  157. 

World's  Chemical  Congress,  122. 
World's  Fair,  Chicago,  122. 
Woulff,  232,  241. 
Wrampelmeyer,  208. 
Wroblewski,  207. 
Wurtz,  Adolf,  6,  191,  192,  199,  206. 

Yale  University,  119. 

Zeeman,  Pieter,  65. 
Zimmermann,  207. 
Zincke,  187,  188,  206. 
Zurich,  University  of,  70. 


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